Earth Science Lessons
The Rock Cycle
• The Rock Cycle...Rocks are dynamic! In this lesson you will learn, wherever you start on the rock cycle, change occurs over time. Magma can cool to produce intrusive igneous rock, or it can erupt to produce lava and later extrusive igneous rock. Sedimentary rock can weather and erode, producing more sediment which may then be carried by rivers to a new location, only to result in the formation of new sedimentary rock. You will also explore the interaction between plants and solid rock and learn how plants can actually be an “agent of change” causing rocks to weather and erode. Rocks are a dynamic feature on Earth, not constant and static, but changing over time, causing renewal of the surface and its features.
The Earth Changes
• Geologic Time...Have you ever looked through a photo album or scrapbook? These types of books show the history of people or families. Looking through a photo album lets you put important life events in order and watch changes over time. You can also create time periods in your own life history. For instance, you might have pages just for the years when you were a baby, toddler, or preschooler. Important events such as first words, first steps, or the first day of school would be milestones or turning points in each of these periods. Dates on pictures might give the information needed to figure out an age or how long ago something happened. The Earth has a history, too. Just like in your life, the Earth's history can be divided into different time periods, each having important events. Also like you, if we were to look at the Earth's photo album, we would see that today's Earth looks much different than when the Earth first began. The history of the Earth is called geologic time and the study of the Earth is called geology. Scientists who study geology have created their own "photo album" of the Earth's beginning, history, time periods, and important events. They have done this, not with photos, but by determining the age of rocks. As you go back through geologic time, consider the following:
• Erosion...Imagine yourself walking on a beach. You feel the sand between your toes, the sea breeze blowing through your hair. You hear the waves crashing on the cliffs in the distance. If you have ever visited a beach and actually had an experience like this, you probably were not thinking about erosion, but a beach is a perfect example of erosion at work. Erosion is the movement of rock particles, like sand. The waves and the sea breeze erode the sand, carrying sand particles to different locations which, over time, can change the size and appearance of the beach. Erosion does not just occur on beaches. In fact, erosion is occurring all around us, in every type of environment. If you have ever seen the Grand Canyon, you have witnessed moving water causing erosion. Dust storms are an example of wind erosion. Mudslides and avalanches are examples of the unstoppable force of gravity causing erosion. Even people and animals can contribute to erosion. The Earth’s surfaces are constantly changing due to erosion of all types.
• Natural Resources...Our Earth is covered with vast amounts of water, soil, and trees. Its atmosphere is abundant with oxygen and other essential gasses vital to supporting life. Water is essential to grow food, drink, and wash. Soil must be rich in nutrients for plants to flourish. The air we breathe contains oxygen, which is necessary to survive. Trees and forests provide shelter to animals and wood to build homes. We rely on all of these natural resources in our everyday lives. However, natural resources are at risk of being destroyed and depleted. Our choices in the amount and use of our natural resources have not always been wise. Our habitats are quickly declining and we now are seeing drastic reductions in animal and plant populations, breathing contaminated air, and drinking water that may not be safe.
Earth: Surface and Inside
• Inside the Earth...There are four main layers of inner Earth, which are then divided into smaller layers. The crust is thin compared to the other three layers. However, for humans, it is the most important because it supports life. The deeper layers are made of heavier materials; they are hotter, denser, and under greater pressure than the outer layers.
• Earthquakes...When continental plates crash into one another and spread apart, the landscape of the Earth will experience vast changes due to the energy that is released. We feel these changes in the form of earthquakes. Luckily, we cannot feel most earthquakes, although instruments can record them. Most earthquakes take place along faults in the top layer of the Earth's surface. When the faults shift, shock waves, also known as seismic waves, flow through the Earth. These waves can destroy enormous areas of land, demolishing buildings, bridges and other massive structures. Scientists who study earthquakes are called seismologists. They study aspects of earthquakes such as level of destruction, magnitude, duration, intensity, and shaking. Sometimes, extremely strong earthquakes cause millions of dollars in damage and kill hundreds. Large earthquakes take place about twenty times a year, also causing millions of dollars in damage and harming numerous people.
• Volcanoes...With one explosion, a volcano can change the earth, flatten forests, hurt living beings, and create new land. Everyone wants to know which volcano will explode next and when it will happen. Scientists continually try to predict the times and locations of future eruptions by using new instruments and information they gather from active volcanoes. A volcano is defined as an area, usually above ground, that lets magma below the Earth come to the surface. Gases, rock, hot ash, and lava are just some of the materials that flow once a volcano explodes. Mudslides, avalanches, coatings of ash, floods, and tsunamis are just some of the things that might happen in an area after an eruption.
The Earth's Air
• The Atmosphere...Have you ever lost a balloon? Maybe you lost your grip on the string and watched the balloon go up, up, up until it was just out of reach. Maybe you stood there, watching it float higher and higher in the sky. Did you wonder where it went? Or how high could it actually go? What we call the “sky” is really a mixture of invisible gases surrounding the entire planet, called the atmosphere. Your balloon could only reach the very bottom levels of the atmosphere, even though it seemed to go really high. The atmosphere actually extends to space and goes through changes that allow scientists to divide the atmosphere into different layers.
The Earth's Weather
• Weather Patterns and Climate...This lesson will allow you to study some of those things that help scientists learn about weather patterns and climate. You will study how winds, air pressure, temperature, air masses, rain, sleet, snow, fog, and humidity, or moist air, determine the weather. Climate is weather over a long period. Climatologists study weather patterns to help understand what the climate will be in areas all over the world. Oceans, clouds, distance from the equator, and height above sea level also decide climate and seasons.
• Wind, Rain, Hail, and Humidity...Envision an eight-inch hailstone crashing through your roof. Consider walking through a wind gust of 100 miles per hour. Imagine sweating while walking through the most humid place on Earth. Visualize the amount of water that you would witness flowing through your house if three feet of rain fell during one rainstorm. Though not always this extreme, the climate does indeed affect every place in the world, every single day. The water cycle is the driving force behind much of our weather. Water rises with heat and eventually falls back to the ground due to gravity. While aloft in the clouds, the water takes several forms of precipitation, clouds, and humidity. Wind pushes the moisture through the jet stream to different locations.
• Cloud Formation...Anywhere in the world, people can look at the sky and observe clouds. Some like to find figures and designs in the white, puffy shapes; others prefer to understand why they form and what types of weather they foretell. We can see clouds nearly everyday. That is probably why clouds can be found in all sorts of stories and picture books. Many factors help to make clouds. Water vapor in the air, wind currents, temperatures, and the amount of dust in the air all contribute. Clouds can be light and wispy like a feather or a dark and foreboding mass. Without clouds, precipitation will not fall to the Earth and renew the water supply. Without this water, life does not exist. Clouds can form near the ground or as far as fifty-three miles above the Earth’s surface. Their colors can be white, blue, red, orange, green, and black depending on the light that it filters. They are part of the protective layer around the Earth that blocks out some of the sun’s dangerous rays. They also keep in some heat and help create winds.
• Hurricanes: The Eye of the Storm...Hurricanes have hit locations the world over and will continue to do so. Meteorologists, forecasters, and researchers, continue to develop and use new weather instrument technology to learn about and track hurricanes. The more these weather experts learn the better they can predict the nature, intensity, and likely paths of future hurricanes. Citizens would do well to heed their warnings and prepare ahead of time when killer storms are headed their way. Without these hard-working experts, hurricanes would pose a far greater threat each season than they do today.
The Water Cycle
• The Water Cycle...The water cycle, also known as the hydrologic cycle, is the continuous change of water from one state to another on Earth. The process involves the atmosphere, land, surface water, and ground water. Driven by the heating and cooling processes of the sun and atmosphere, the water moves through the cycle, changing between liquid, solid, and gas. The physical processes of evaporation, precipitation, infiltration, runoff, and subsurface flow drive water. The water cycle has no beginning and it has no end, but we know that it is vital to all living things on Earth, including plants, animals, and humans.
• Forming Streams and Rivers...The formation of rivers, lakes, and streams can be traced back to the water cycle, as they are formed as a result of precipitation. Over time, small streams can develop into large bodies of water that are an ecosystem of their own. These fresh water systems, which also include lakes and wetlands, have been critical to the establishment of civilizations throughout history. In ancient times, societies evolved in areas located closest to water. Bodies of water are absolutely essential to humans, not only for drinking, but also for agriculture, production of energy, transportation, industry, and waste disposal.
• Ocean Make Up...Much of our planet Earth appears blue from space because more than 70% of the surface is covered by oceans. The oceans serve many functions. They keep temperatures moderate by absorbing incoming solar radiation that they store as heat energy. The always-moving ocean currents distribute this heat energy around the globe, warming the land and air during winter and cooling it during summer. The oceans regulate climate, provide resources such as fish and minerals, and potentially offer cures for disease. They are home to half of the world’s organisms, and new species are being found almost daily. Although life likely began in the oceans, we know more about the moon than we do about these mysterious depths.
The Earth and the Universe
• The Solar System...The Solar System is our space neighborhood. The Sun is at the center and provides light, warmth, and energy to everything in the Solar System. The planets, along with hundreds of moons and thousands of asteroids, are our neighbors. Everything in the Solar System follows the same path at all times. Our Solar System is like a finely tuned machine, in which each part performs its own functions and duties. The Sun contains 99.8% of the mass of the entire Solar System. It creates 386 billion watts of energy; that is a lot of energy! Without the Sun, there would not be a Solar System. There are eight known planets in our Solar System, with Pluto recently being renamed a dwarf planet. Astronomers continue to send spaceships out to discover new and exciting planets, moons, and asteroids. Scientists spend great amounts of effort studying those space objects that we have already discovered. Collecting samples from the surface and drilling into the crust can turn up fascinating discoveries.
• The Earth, Sun, and Moon...Here on Earth, we often take the light and heat provided by the Sun for granted. The Moon is often just something to look at in the night sky. However, the Earth's relationship with the Sun and the Moon is much more important. The motion and gravitational pull of the Sun and Moon cause great changes to the Earth on a regular basis. Predictable changes in the level of the waters on Earth called tides occur monthly. Other phenomenon such as lunar and solar eclipses occurs on a much rarer basis. Exploring the Moon and discovering its origin can provide hints to the origin and history of Earth. By making expeditions to the Moon, sending space telescopes to capture images and video of the Earth and Mon, and collecting specimens, we hope to continue to find out more and more about the balance of the Earth, Sun, and Moon.
Earth Science Fields
• The Study of Astronomy...What comes to mind when you hear the word Astronomy? Perhaps you think of space, and the different meteors, constellations, and galaxies containing thousands of stars. Prepare for a virtual journey where you will be introduced to some stars in the sky, and to some star astronomers who helped the citizens of Earth become more acquainted with space!
• The Study of Climatology...What kinds of questions do people consider when visiting or moving to a new place? One of the first questions is usually, “What's the weather like?” Weather affects us everyday, everywhere we go. Whether you live in an area prone to heat waves, or up north where winters are long and dark, knowing how the weather changes over a period is important for planning and survival. The weather over an extended period is called the climate. Studying climate is a job for special scientists called climatologists. However, understanding the climate is good for everyone. Let's find out why.
• The Study of Geology...We will discover that not only can geology be an extremely important part of your life depending on where you live, but also that studying geology can be important to some of the little things everyone does every day. Volcanologists and seismologists can tell people who live near plate boundaries or hot spots when they should evacuate. Petroleum geologists help oil companies find new sources of oil that we can use for the gas to travel to school. Paleontologists help museums expand their collections, and hydrogeologists help us find and take care of sources of clean water. Medical Geologists can help make homes and buildings safer, and astrogeologists can bring us fascinating information about other planets and moons.
• The Study of Meteorology...Who studies all these weather phenomena that interrupt our regularly scheduled programming? The scientists who study tornadoes and other weather events are called meteorologists. Let's find out more about all the different things meteorologists can discover about the weather.
• The Study of Oceanography...If you have ever been to the beach or swimming in the ocean, you may have wondered what else was swimming with you. You may have a favorite aquarium you like to visit. Many people have made careers out of their love for the ocean. They are called oceanographers, and some have become quite famous through their discoveries about the ocean's history, aquatic life, and the mysterious underwater environment. Let's find out how they accomplish their discoveries about the sea.
• States and Properties of Matter...Matter is something that takes up space. Not only is it solids and liquids, which you can see, but it includes gases, including the air you breathe. Plasma is a fourth type of matter; although it is similar to a gas, it is electrically neutral. Bose Einstein Condensation is now considered the fifth state of matter. It is different than the other forms; all the atoms move together. Matter is measured by the amount of space it takes up; this is called mass. Its volume can also be measured. These two measurements are used to find the density of matter.
• Structure of Matter...Atoms are the small particles that make up everything from your television set to the water you drink to the hair on your head. The number of protons determines the kind of an atom. The elements on the periodic table are made up of atoms. Each element has a different number of protons, which is the element's atomic number.
• The Periodic Table...The earth is made up of elements. Some of the most common elements are hydrogen, helium, oxygen, carbon, iron, and nitrogen. Elements are made up of atoms. Atoms are made up of protons, neutrons, and electrons. The number of protons determines the atomic number of the element. The number of electrons is the same as the number of protons. The periodic table is a chart that lists all of the elements. It is organized by each element's atomic number.
• Mineral Formation...There are a variety of minerals on Earth. In addition to appearing different to the eye, minerals also have unique physical and chemical properties. Like all things on Earth, minerals are made up of atoms, the smallest bit of matter. Native elements are minerals made up of one type of atom. Complex minerals are made up of more than one type of atom.
• Mineral Uses...Minerals are used to make buildings, driveways, and metals. They are even used in common objects, such as powders, coins, toothpaste, and light bulbs. They also light up the sky with different colors when used for fireworks. Minerals even exist naturally in foods you eat. Your body needs minerals to be healthy. Examples of minerals are iron, calcium, talc, silver, sodium and zinc.
• Gemstones...Gems come from gemstones, which are naturally formed. Some gemstones come from plants and animals. Pearls form from oysters; amber forms from tree sap. These are referred to as organic gems. Just like rocks, the journey of each gemstone is unique. Gemstones vary from the way they look, to how they form, to their crystal structure, to how valuable they are. Some of the most common gems are diamonds, rubies, and emeralds. Gemologists use special equipment to identify gemstones. They may look at their color and crystal structure, which vary depending on the gemstone.
The Earth's Rocks
• The Rock Cycle...As you can see, the rock cycle is forever occurring. Rocks are constantly changing to and from igneous, metamorphic, and sedimentary. The earth causes these changes both on and beneath its surface. Igneous rocks form from volcanoes. Some rocks cool quickly. They may become glassy, such as obsidian or have pockets of air, such as pumice. Not all rocks cool quickly. Dense rocks like granite form beneath the earth's surface. Rocks formed on the earth's surface are called extrusive igneous rocks; rocks formed beneath the earth's surface are called intrusive igneous rocks. Metamorphic rocks form from heat and pressure beneath the earth's surface. These rocks look very different after they have morphed. Sedimentary rocks form from sediments, such as clay, sand, and shell building up in lakes, rivers, and oceans. Rocks can be cemented together or layered on top of one another. They can also come from remains of plants and animals. All these changes make up the rock cycle.
• Igneous Rocks...Igneous rocks are one part of the rock cycle. Rocks that form from magma underground or volcanic eruptions make up the variety of igneous rocks. Intrusive rocks are igneous rocks beneath the earth's surface; extrusive rocks are ones formed on the earth's surface. One factor in the kind of igneous rock that forms is how it cools. Rocks that cool quickly are often glassy since minerals do not have time to form. Rocks that cool slowly have larger minerals.
• Sedimentary Rocks...The world of rocks, particularly sedimentary rocks, provides a wide variety of benefits, beauty, and resources for all of us. Sedimentary rocks come to us through a natural process called the rock cycle. This category is one of the three main divisions of rocks. (Igneous and metamorphic are the other two). The rock cycle consists of weathering, erosion, transportation, and deposition. A vast number of rocks you are apt to find are sedimentary rocks, but they might look very different in size, shape, and color. Because sedimentary rocks exist and have provided us with countless fossils, we are able to uncover a multitude of stories about the history of our earth. Thus, we know when plant and animal species existed and perhaps the geologic time they disappeared. Because sedimentary rocks exist, we are able to enjoy the splendor of magnificent caves, with their spectacular stalactites and stalagmites. Because they exist, we are able to employ them for construction projects. Because they exist, we are provided with coal, oil, natural gas, and petroleum.
• Metamorphic Rocks...If you were to look at rocks, you may notice that some resemble each other. They may be flatter or have more stripes, but they definitely have similarities. Metamorphic rocks form from igneous and sedimentary rocks that have been heated and smashed with such temperatures and pressure that they actually form new rocks. On the next pages, you will learn more about how they form as well as get to look at examples of these rocks.
Earth's Changing System
• Geologic Time...The journey back through the billions of years of geologic time has shown many changes in our planet Earth. We started in the Hadean Era, when planet Earth was forming an atmosphere and crust. Our journey continued as first life forms changed the atmosphere to one that was oxygen-rich, which allowed life to explode in the Paleozoic Era. Continents moved and changed position as we moved into the Mesozoic, when reptiles ruled the land. At the end of that era, a major extinction took place, which allowed mammals to become more numerous. If we relate this amount of history to one calendar year, we would not have arrived until the last few hours of the year! Through the study of rocks and fossils, geologists have been able to determine the exact age of the Earth and the dates of these different periods of the Earth's history. The more we uncover the facts of the past, the clearer the formation of the Earth will become and the better picture we will have of the possible future of the planet.
• Weathering...Processes of mechanical weathering break up rock into smaller pieces but do not change the chemical make-up. The processes of chemical weathering transform rocks and minerals exposed to water and gases into different rocks and minerals, some of which can be dissolved away. In nature, mechanical and chemical weathering usually occurs together. Weathering is a long, slow process, which is why we think rocks last forever. We also tend to think of weathering as destructive and a bad thing because it ruins buildings and statues. However, as rock is destroyed, valuable products are created. The major component of soil is weathered rock. The growth of plants and the production of food is dependent on weathering. Some metallic ores, such as copper and aluminum, are concentrated into economic deposits by weathering. Dissolved products of weathering are carried in solution to the sea, where they nourish marine organisms. And finally, as rocks weather and erode, the sediment eventually becomes rock again.
• Global Soil Properties...Today you are going to learn about dirt. Yes, that's right, dirt. Well, actually soil. You might be wondering why on Earth you have to learn about this. And that is the answer- the Earth. The roughly 10% of the Earth that is covered with soil is the basis for many human activities, most importantly farming. Without dirt, you would not be able to eat many of the things you do, or enjoy many of the other activities that you might do everyday without even thinking about the impact of dirt.
• Erosion...The Earth's surface is constantly changing. Weathering processes result in rocks being broken into smaller pieces that are able to move. Many different factors that result in the motion of these particles derive from erosion. Gravity is a force that is at work in all types of erosion, and its full force is witnessed with mass-wasting events, such as rock slides and debris flow. The wind is also an agent of erosion, by blowing loose soil to new locations and breaking down other rocks by abrasion. Water is the most active agent of erosion on the planet, resulting in many changes to the appearance of the landscape. As the water of a river and stream flows, it erodes the channel. As time goes by, this will result in a deepening of the river bank and eventually a valley that meanders downhill. Wave crashes on the coastline cause erosion as well. All of these processes are just one part of the Earth's rock cycle.
• Humans and Erosion...The human causes of soil erosion are simple to understand, but are difficult to fix. How do we stop beaches eroding due to man-made structures such as seawalls? Do we stop building seawalls and homes on the beach? Or do we spend more taxpayer money for more expensive solutions such as beach renourishment? How do we stop poor farmers world-wide from practicing farming techniques, such as slash-and-burn, that erode the soil when they have families to feed? Who will pay for the education and training they need? As you can see, the problem of human and soil erosion does not have a simple solution, and it will be up to future leaders world-wide to continue working on this complex issue.
• Inside the Earth...Remember when you and your friends thought they could dig your way to China? After digging for a few hours, you realized it was not possible. But, what it if were? Great mysteries lie right under your feet. Because no one has actually explored inner Earth, no one can testify what is down there. Explorers have burrowed only about 7 and 1/2 miles down. That is impressive until you appreciate the fact that you may need to travel as many as 4,000 miles to get to the center of the Earth. Investigations into the structure of inner Earth has shown that there are four layers, which are then divided further into sub-layers. The crust is relatively thin in comparison to the other three layers. However, for humans, it is the most important because it supports life. The deeper layers are composed of heavier materials; they are hotter, denser, and under much greater pressure than the outer layers. The next layer in is called the mantle. Most of the Earth's mass is in the mantle. Estimates suggest it could be as hot as 1000 degrees C suggesting that that the mantle is solid but can slowly change shape. The core is divided into the outer and inner core because they appear to have diverse characteristics. The core is so hot that the outer core is molten while the inner core is under such extreme pressure that it remains solid.
• Plate Tectonics...The plate tectonics theory is an idea that has completely changed the way we think about the Earth. According to the theory, the surface of the Earth is broken into large plates that change position over time. When the edges of these plates come into contact, earthquakes, volcanoes, and mountain building occur. The continent and ocean plates float on the lithosphere, which constantly churns because of the action of convection currents beneath the surface of the Earth. Plate tectonics also includes the concepts of continental drift and sea-floor spreading. Continental drift is the movement of continents over the Earth's surface while sea-floor spreading is the creation of new ocean crust.
• Earthquakes...When continental plates converge, diverge, or transform, the landscape of the Earth will change because energy must be released that has built up over time. Luckily, most earthquakes cannot be felt by us, although they can be recorded by instruments. Most earthquakes take place along faults in the upper twenty-five miles of the Earth's surface. When the faults shift, shock waves, also known as seismic waves, flow through the Earth. These waves can destroy enormous areas of land, buildings of all shapes and sizes, and kill in a blink of an eye. Scientists who study earthquakes are called seismologists. They study earthquake features such as amount of destruction, magnitude, duration, intensity, and shaking. Very large earthquakes cause millions of dollars in damage and kill hundreds, but fortunately occur worldwide only once every few years. Large earthquakes take place about twenty times a year, causing millions of dollars in damage and harming many people.
• Volcanoes...Volcanoes have piqued human interest for thousands of years. With one eruption, a volcano can reshape the earth's landscape, destroy forests and living beings, create new islands, and demonstrate Mother Nature’s power. Scientists attempt to predict the times and locations of these great eruptions by ever improving technology. A volcano is simply defined as an area, usually uplifted, that allows magma below Earth to come to the surface. Gases, rock, and lava are just a few of the materials that flow during an eruption. Eruptions can cause lava flows, hot ash flows, mudslides and avalanches, coatings of ash, floods, and tsunamis.
• The Atmosphere: Compostion and Levels...The atmosphere is an envelope of gases that surrounds the Earth. The edges of the atmosphere extend into outer space. As we move through the atmosphere, we see many changes. Going up from the surface, the temperature drops and the air pressure becomes less as the air thins. Then, we reach the stratosphere, where the temperature begins to climb once again as the ozone molecules absorb harmful ultraviolet light from the sun. There is no weather here and the air is still. Continuing upward, we reach the mesosphere and the temperatures are very low, lower than any temperature reached on Earth. The gases become thinner and thinner, and in the thermosphere, there are few molecules. The few molecules of air are moving fast, though, making for incredibly hot temperatures, so hot that molecules lose their electrons, resulting in charged particles that are helpful for us back on Earth. We might see the space shuttle here, or satellites, and as we continue on, the atmosphere gradually fades away.
• Human Effect on the Ozone...Ozone is a naturally occurring chemical in the stratosphere that serves to protect the Earth. Human activities, though, have affected this protective layer. The use of CFC's in aerosols, air conditioners, and refrigerators, just to name a few, has contributed to the destruction of protective ozone. The destruction of the ozone layer will have serious consequences for both humans and the environment. The Montreal Protocol brought many countries together to form an agreement to ban the use of CFC's, with hopes that the ozone layer will repair itself. Ozone also occurs closer to home, in the troposphere. This “bad” ozone is formed by reactions between various compounds, such as nitrogen oxides, that are produced by factories and vehicles. The Clean Air Act of 1970 was passed in an effort to reduce the amount of ozone pollution. However, Ozone Action Days still occur on a regular basis in many big cities, and people are still suffering from the health effects caused by ozone pollution.
• Global Warming...Many claim that global warming may be the single largest threat to our planet. For decades, human factories and cars have spewed billions of tons of greenhouse gases into the atmosphere and the climate has begun to show some signs of temperature increase as a result. Legislators have passed laws restricting what factories can release form their smokestacks. Doomsayers proclaim that if we don't reduce greenhouse gas discharges, then seaside cities could disappear under a flood of water and weather patterns across the world could change Conversely, there are others who believe that global warming will result in little more than warmer winters and increased plant growth. They disagree with the pessimistic measurements, claiming that the uncertainly of weather and climate patterns cannot possibly predict drastic changes. They maintain that restricting factory emissions may cause the world economy and human society more harm than any amount of global warming. This lesson is designed to present the known facts and both sides of the issues. You can determine for yourself if this is truth or hoax.
Climate and Weather
• Weather Patterns and Climate...Weather patterns and climate have resulted in some of the most creative sayings and legends. Earlier cultures tried to explain trends and coincidences that had no scientific explanation based on observations, measurements, and descriptions, while collecting records about temperature, air, wind, and clouds. With this information, people created tools to measure weather and looked for consistent weather patterns. This lesson will allow you to explore features that affect weather patterns and climate, such as atmospheric pressure, winds, temperature, air masses and fronts, precipitation, humidity, clouds, seasons, ocean currents topography, latitude, and altitude. Based on those concepts, you will begin to develop weather forecasting skills as well as analyze a variety of weather legends such as: if there is a halo around the moon, it will rain; “thunder in spring, cold will bring”; “red sky in morning, sailor's warning; red sky at night, sailors’ delight.”
• Wind, Rain, Hail, and Humidity...The water cycle plays an important role in the air we breather, the plants that grow, and the formation of land. When you add air pressure to the mix, you get weather in the form of precipitation, humidity, and wind. The water particles in the air collect together in clouds and remain there until gravity brings them back to the Earth in the form of rain, hail, mist, fog, and snow. Prior to precipitation, humidity is determined by the amount of moisture in the air. Wind or air that is pushed from high pressure areas to lower pressure areas, moves humidity and precipitation from one location to the next. Without wind, your local weather would not change much from day to day. When you step back and look at these processes, you will notice that everything is interconnected. Who knew that weather played such an important role in the system of life!
• Thunder and Lightning...Lightning, the thunderbolt in mythology, was long thought to be the weapon of the great gods such as Zeus and Thor, who struck mere mortals on a whim. Indian tribes in North America believed that the flashing feathers of a mystical bird caused lightning. Those same wings produced the sound of thunder. Later myths suggested that angels produced thunder while bowling in the heavens. Today, people turn to science rather than superstition to explain lightning and thunder. Even as scientists begin to understand the mechanics, they still recognized that lightning has the awesome power to destroy property and human life. History credits Benjamin Franklin with performing the first truly scientific study of lightning in the eighteenth century. Prior to that time, scientists separated positive and negative charges by rubbing together two different materials and storing the sparks in structures to study. In this lesson, you will study more science behind thunder and lightning.
• Tornadoes...Tornadoes happen all over the world, most often in the United States during the spring and summer months. In an average year, up to 800 tornadoes can touch down in Tornado Alley, the area from the east coast to the Rocky Mountains. Those who study weather define tornadoes as quickly spinning air coming down from a severe thunderstorm with winds turning as much as 300 miles per hour. These twisters throw heavy objects such as cars into the air, flatten houses, and uproot trees.
• Hurricanes: The Eye of the Storm...Hurricanes are destructive natural forces of nature that cannot be prevented. They are highly organized weather systems that require the participation of various factors such as water temperatures, air temperatures, air pressure, and winds. They occur in the tropical regions around the globe and have caused massive damage to homes, buildings, roads, trees, and living beings. By studying past hurricanes and using science and technology to study current tropical storms, we can enhance the ability of large cities to prepare for the worst of storms. The devastation of past storms such as Katrina, which hit the Louisiana/Mississippi coast in September 2005, will be remembered for years to come. Hopefully officials and specialists will continue to work diligently to better prepare future populations for the havoc of these tempests.
• Cloud Formation...Cloud formation relies on the amount of water vapor in the air, wind currents, temperatures, and the amount of dust in the air. Without clouds, precipitation will not fall to the Earth, renewing the water supply. Without this water, life does not exist. Clouds can form near the ground or as far as 53 miles above the Earth's surface, and vary in color. They are part of the protective layer that strains out some of the sun's dangerous rays, retains some heat, and creates winds.
• Monsoons and Drought...The word "monsoon" comes from the Arabic mausim, which means "a season." It first described the winds over the Arabian Sea, which blew from the northeast for six months and from the southwest for six months. Temperature differences over land result in seasonal pressure differences are one factor that contributes to monsoons. This pressure difference, along with the northern storms during the summer, causes the tropical moisture to be forced northward, toward the lower pressure in the low levels of the atmosphere. This shifts the winds over a large area and enough moisture accumulates to trigger seasonal rains. Although we do not understand the precise cause of the monsoons, we know that air pressure, temperature, and snow cover are primary factors.
• The Water Cycle...Earth's water supply remains constant. Water in the atmosphere is replaced once every 8 days. On average, water is renewed in rivers once every 16 days. Recycling can take hundreds to thousands of years in large lakes, oceans, and groundwater. In many places, groundwater is being used by humans much faster than its renewal times. Where this occurs, water is becoming a nonrenewable resource. Rising populations remove more water from rivers, lakes and aquifers. This threatens future water supplies. A larger population also creates more wastewater. Farms add pesticides and fertilizers to the groundwater. Industrial wastes carry toxic chemicals and bacteria. All these factors reduce the amount of clean water. Current practices threaten both the quantity and quality of water available to future generations.
• Forming Streams and Rivers...Rivers and streams contain surface water runoff that moves from higher to lower elevations. Rivers provide drinking water, irrigation water, transportation, hydro-electrical power, drainage, food, and recreation opportunities. At the source of a river, the water is relatively pure. As the water flows downstream through its watershed, it picks up silt and minerals from the soil and rock in the river bed. Erosion changes the shape of the river and the land around it. Natural and man-made substances, such as animal and human waste, farm runoff, urban runoff, and waste from factories, enter river water as it flows downstream. Keeping pollutants out of water is everyone's responsibility.
• Ocean Make Up...Energy from the Sun falls unequally over Earth's surface. Most of the Sun's energy strikes the Earth near the equator. This leads to large temperature gradients between the equator and the poles. Movement of the oceans is controlled by these temperature differences, as well as wind, gravity, and the Coriolis Effect. The result is a transfer of heat, from the equator to the poles. This means that the oceans are an extremely important part of the Earth's climate control system. The oceans also contain rich resources of food and minerals, and are used for the transportation of goods throughout the world.
• Waves and Tides...The sea and land are constantly changing, as water circulates around the globe in 1000-year cycles. Continents drift slowly around the globe. Mountains rise up and erode back to soil. We don't notice these changes because they are slow and gradual. But thanks to ocean waves, noticeable changes on a beach can happen during a single storm. Sand can be pulled out to deeper water, causing a beach to disappear within several years. Sediment deposited by longshore drift can create new landforms farther down the beach. On the other hand, the buildup of sand often protects harbors and estuaries, which provide many resources that humans use.
• Deep Ocean...Most of our knowledge about the deep ocean has been discovered in the last 50 years. Landforms on the ocean floor help scientists understand Earth's geological processes and history. Hydrothermal vents on mid-ocean ridges support fantastic ecosystems and exotic communities of life. Heat from the Earth's interior, rather than the sun, supports these life forms. Some believe that these organisms may hold clues to the origin of life on Earth. They may lead us to think differently about life on other planetary bodies. So far, we have only studied a very small percentage of the ocean floor. New instruments and deep submergence vehicles will greatly increase the exploration of “inner space” in the 21st century.
The Greater Universe
• Exploring Space...The ever-expanding universe is a vast collection of millions of entities. We have located and named only a small portion of them all. By studying the other galactic bodies through high-powered telescopes, infrared research, manned space missions, and satellites, we hope to learn more about our own Earth's history and where we are going from this point. Astronomy is an exciting field where new discoveries are rapidly made. The rate at which we attain new information is mind-boggling. Here on Earth, we have the unique mix of elements and gasses that provide for life. Could it be possible that there is another galaxy out there with a planet similar to Earth?
• Stars and Galaxies...Galaxies are colossal conglomerates of stars that make up the universe. Each galaxy is like a smaller, living universe existing on its own merit. Galaxies will sometimes invade one another's space, colliding and performing spectacularly violent events. The billions and billions of stars that are found within the universe contribute the uniqueness of the galaxies. Each star presents its own distinctive personality and progresses through an amazing metamorphosis over millions of years. Ancient astrologers created mythological names for the different clusters of stars that help locate various objects in the night sky. Star-gazing takes on a deeper meaning when you understand more about the intricate system that operates above.
• Meteors and Comets...Whether it is a meteoroid, an asteroid, or a comet, there are innumerable objects that exist in space. We can observe and study some of the larger bodies, and these give us further clues about our solar system's history and makeup. With billions of interplanetary entities entering our own atmosphere, we are constantly reminded that the Earth is not alone. In fact, we coexist with billions and billions of other objects right in our very own solar system.
• The Solar System...From the sun to the dwarf planet, Pluto and with all of the asteroids, meteoroids, and moons in between, the solar system is a remarkable and intricate organization. The powerful sun keeps all of these objects in balance. Astronomers continue to explore the other planets to look for clues to our past and to find out where our solar system is headed. To think that our solar system is but one of many solar systems in the universe is an amazing fact to ponder.
• The Sun...The Sun is located at the center of our solar system and is the control center of all operations. The orbiting planets and moons depend upon the sun's constant gravitational pull. Here on Earth, we rely on the Sun's heat and light energy to provide us with food and warmth. The Sun is a massive swirling glob of hot gas. In some areas, intense heat causes massive explosions at the surface that reach far out into space and can even affect us here on Earth. In other areas, the temperature actually cools down temporarily and we can see these dark areas called Sun spots. The Sun makes up over 99% of our entire solar system. Without this amazing star, our solar system would cease to exist. It has been around for approximately 5 billion years and is expected to last another 5 billion years. So we should not see any major differences in the Sun's operations anytime soon.
• The Earth, Sun, and Moon...The Earth's relationship with the Sun and the Moon is much more important than simple illumination or aesthetics. The motion and gravitational pull of the Sun and Moon cause great changes to the Earth on a regular basis. Exploring the Moon and trying to figure out its origin can provide hints to the origin of Earth and its history. By making expeditions to the Moon, sending space telescopes to capture images and video of the Earth and Moon, and collecting specimens, we hope to continue to discover more and more about the balance of the Earth, Sun, and Moon.
• Expedition Mars...The Red Planet is of utmost interest to astronomers today. While Mars is only one-tenth the mass of Earth, it is the seventh largest planet in the solar system. The climate ranges from negative 207 degrees to 81 degrees. While Earth's atmosphere is 79 percent nitrogen and 20 percent oxygen, Mars' atmosphere is 95 percent carbon dioxide and only 1.6 percent oxygen, making it impossible to breathe on its surface. Mars holds numerous secrets that we hope to understand better through this lesson.