The earth's atmosphere is about 430 miles thick. Without this layer of gases to protect us, we could not live. We would be scorched by the sun during the day and frozen at night. Most of the atmosphere is a thin mix of gases that is calm and unchanging. But the lowest 7 miles--the layer in which we live and breathe--contains all the weather we experience, and is thick with gases, water, and dust. As the sun warms the land and sea beneath it, the heat keeps this lower 7 miles swirling and churning. It is the constant swirling of this lowest layer, called the troposphere, that gives us everything we call weather--from the gentle showers to raging hurricanes and tornadoes.
The earth has a clear pattern of wind circulation that results from the effect of the earth's rotation and the way that the heat of the sun is distributed. It has become easier to view these cycles and patterns because of photos that can now be taken from satellites orbiting the earth. These global patterns cause weather to occur in cycles--the typhoons that are generated from the China Sea and affect southeast Asia--the hurricanes that begin in the Caribbean and affect the southeastern United States and Central America--the tornadoes that travel through the American midwest.
Sample some of the following activities to learn more about seasonal cycles of the earth.
The following are places to go (some real and some virtual) to find out about seasonal cycles of the earth.
Explore a temperate deciduous forest. This particular biome exhibits all 4 of earth's seasons. Find out how the animals of this biome adapt to its seasonal changes.
Visit schools around the United States as they participate in the Globe program. Globe is a worldwide network of students, teachers, and scientists working together to study and understand the global environment.
In the past, the natural flooding of the Colorado River was part of the shaping of the Grand Canyon. Today, these natural flood cycles have been eliminated by the building of dams and the control of the river's natural flow.
The National Weather Service is THE place to go to find out about weather and its cycles.
Visit a floodplain. The seasonal cycle of rivers flooding is a normal part of nature and is part of the way that fertile soil builds itself up. In fact, the ancient Egyptians used to refer to the annual flooding of the Nile as the "gift of the Nile" and they welcomed the benefits that it brought. In modern times, problems arise when humans build cities and homes in floodplains and try to rechannel rivers to avoid flooding.
Check out states' highest recorded temperatures. Check out state's lowest recorded temperature. Here's a handy temperature calculator if you need to convert between Fahrenheit and Celsius.
Spend time with scientists who study volcanoes. The eruption of volcanoes can actually affect the normal flow of seasons of the world. When there are huge explosions, large amounts of gas, ashes, and dust burst into the atmosphere. These particles are blown about by winds and may stay in the atmosphere for months or years. These particles stop some of the sun’s rays which can lower temperatures and affect food production. In 1815 the Tambora volcano erupted in Indonesia, spewing enormous amounts of particles into the atmosphere. The following year, areas in Europe and North America had temperatures that were far below normal. Scientists, therefore, call 1816 “the year without a summer”. This cold summer caused crop failures and food shortages.
Spend time with the resilient people of Indonesia, who survived the devastating Indian Ocean tsunami in 2004.
Spend time with ancient peoples who understood seasonal cycles. Many of monuments they left behind were designed to celebrate the longest and shortest days of the year. In the northern hemisphere, the spring equinox is March 20th or 21st, the summer solstice is June 21st, the autumn equinox is Septembers 22nd or 23rd, and the winter solstice is December 21st or 22nd. Places such as Stonehenge in England and Hovenweep in southern Utah were aligned to catch the rays of the sun in specific places on the longest and shortest days of the year.
The seasons of the earth are a result of the tilt of the earth and its rotation around the sun. The journey around the sun takes one year, and the earth rotates in a tilted position. So depending on the time of the year, either the northern hemisphere or the southern hemisphere is tilted so that it receives more of the sun’s rays which results in summer. Visit the people who make Google Earth. With a visual representation of the earth, it's easy to learn about the earth’s seasons.
See worldwide communities that are affected by flooding. Floods are the most destructive of natural forces caused by seasonal cycles. They cause more loss of life and damage more property than any other natural disaster.
Visit bears in their dens, chipmunks in their nests, and badgers in their burrows. These animals adapt to the seasonal cycles of the earth by hibernating during the coldest times of the year. Many of these animals eat large amounts of food in the summer and fall and almost double their body weight. This energy store keeps them alive during their hibernations months. Their heartbeats and breathing slow down and their temperature decreases in order to save energy.
Visit with some real hurricane hunters. These Air Force men and women fly airplanes right into the eye of hurricanes to gather data.
Meet Hurricane Mitch. He was one the most destructive hurricane in recorded history. He devastated Honduras in 1998. More than 35 inches of rain fell on Honduras over the course of 5 days which caused massive floods and mudslides and killed over 11,000 people.
Talk with stormchasers. They are men and women who are passionate about seasonal weather cycles. Their job is to observe and document severe weather.
Chat with Al Roker. He knows all about weather cycles and can tell you your local weather forecast.
Get to know Jack Frost. He is associated with the seasonal cycles of winter. Jack Frost was originally part of Norse legend and was called Jokul Frosti which means icicle frost. He was the son of the god, Kari.
Visit the people of China who live near the Yellow River. This river has flooded so many times and has damaged so much farmland and killed so many people that it is sometimes called “China’s Sorrow”. Its collective floods have killed more people than any other natural disaster. In 1931 alone, a flood of the Yellow River killed almost 4 million people.
Study climate of the past. It can help us understand earth's climate of today as well as that of the future.
Find out about the forces that make glaciers.
Check out global climate highlights and anomalies. Sometimes weather cycles go awry.
Weather all over the world is affected by ocean currents. Find out more.
El Niño is a weather condition where a warm ocean current that is normally situated off Australia's coast moves east toward the coasts of Equador and Peru. La Niña is kind of like the opposite of El Niño. Its cycle involves strong trade winds and cooler Pacific waters. From NOAA, check out these FAQs about El Niño and La Niña.
Find out the difference between a solstice and an equinox.
Find out about the economic losses that arise from floods, hurricanes, and tornadoes. Select "Flood" and then look at Utah's data.
The greenhouse effect is an increase in the temperature of a planet as heat energy from sunlight is trapped by the gaseous atmosphere. Check out this chart of the greenhouse effect and this one.
The tilt of the earth is 23 ½ degrees. Discover what this has to do with the seasonal cycles of the earth.
Virtually thumb through the old Farmer's Almanac. It has been around since 1792! It has everything you ever wanted to know about planting cycles, weather cycles, and more.
Create a seasonal postcard.
Find out what would happen to our seasons if the tilt of the earth's axis was 0°. (Hint: You would never need your woolen mittens or Bermuda shorts).
Learn more about the seasons of the earth. This information is part of the excellent Weather Dude site. From the same source, find out why the sun is the source of all the weather on the earth--its even responsible for the wind!
Find out if seasons exist at the equator.
Check out the current weather on the sun.
Find out what the weather cycles are that produce tornadoes more often at certain times of the year.
Hibernation information and activities.
Learn the scientific reasons behind Earth's seasons
Are the seasons caused by the distance between the sun and the earth? Is winter colder because during that season the earth is farther away from the sun?
There is a popular misconception that the seasons on the Earth are caused by varying distances of the Earth from the Sun on its elliptical orbit.
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- Farndon, John. Weather. New York: DK Pub., 1998.
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- Llewellyn, Claire. Wild Wet and Windy. Cambridge, Mass.: Candlewick Press, 1997.
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