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OZONE

What is the ozone layer?

The ozone layer is part of the stratosphere, a layer of the Earth's atmosphere that lies about 10 to 30 miles (16 to 48 kilometers) above the surface of the Earth. Ozone is very important to life on the planet because it shields us from most of the damaging ultraviolet radiation from the sun.

Is the ozone layer being depleted?

Scientists have recognized that a hole has developed in the ozone layer, a hole that has been growing since 1979. The hole is located over Antarctica and has been responsible for increased ultraviolet radiation levels in Antarctica, Australia, and New Zealand. As the ozone hole grows, it will increase the amount of harmful ultraviolet light reaching the Earth, causing cancer and eye damage, and killing crops and micro organisms in the ocean.

How much of the ozone layer is being depleted?

Since 1975, scientists believe that more than 33 percent of the ozone layer has disappeared. There is a seasonal factor to the reduction in ozone at any given time during the year, too. At different times, the ozone layer naturally declines or rises. But scientists also know that chlorofluorocarbons (CFCs), which are used for air conditioning, aerosol sprays, halon in fire extinguishers, and the interaction of man-made chemicals with nitrogen in our atmosphere, directly cause ozone depletion. It is a man-made problem that requires a man-made solution.

How do CFCs destroy ozone?

When CFCs rise up in the atmosphere to the ozone layer, ultraviolet rays break them down into bromine and chlorine, which destroy ozone molecules.

CLIMATIC TRENDS

Why is it very wet on one side of a mountain range?

It's much more wet on one side of a mountain than the other because of a process known as orographic precipitation. Orographic precipitation causes air to rise up the side of a mountain range and cool, creating storms. The storms deposit a great deal of precipitation on that side of the mountain and create a rain shadow effect on the opposite side of the range. The Sierra Nevada mountains are an excellent example of orographic precipitation because the mountains of the western Sierras receive considerable rainfall (far more than California's Central Valley), while the eastern Sierras of Nevada are quite dry.

What is a rain shadow?

When the moisture in the air is squeezed out by orographic precipitation, there's not much left for the other side of the mountains. The dry side of the mountain experiences a rain shadow effect because they are in the shadow of the rain.

Can people live in a torrid zone?

The ancient Greeks divided the world into climatic zones that are not accurate. The three zones included frigid, temperate, and torrid. They believed that civilized people could only live in the temperate zone (which, of course, was centered around Greece). From Europe northward was part of the inhospitable frigid zone, while most of Africa was torrid. Unfortunately, this three-zone classification system stuck and was later expanded to five zones once the southern hemisphere was explored. People identify everything north of the Arctic Circle (near northern Russia) and south of the Antarctic Circle (near the coast of Antarctica) as frigid, everything between the tropics and the Arctic and Antarctic circles as temperate, and the zone between the Tropic of Cancer and Capricorn as torrid.

What is El Niño?

El Niño (also known as ENSO or the El Niño Southern Oscillation), is a large patch of warm water that moves between the eastern and western Pacific Ocean near the equator. When the warm water (about one degree Celsius warmer than normal) of El Niño is near South America, the warm water affects the weather in the southwestern United States by increasing rainfall, and is responsible for changes in the weather throughout the world. El Niño lasts for about four years in the eastern Pacific Ocean and then returns to the western Pacific near Indonesia for another four years. When the warm water is in the western Pacific, it is known as La Niña, the opposite of El Niño. When La Niña is in action, we have "normal" climatic conditions.

Where does the name El Niño come from?

The phenomenon of El Niño was discovered by Peruvian fishermen who noticed an abundance of exotic species that arrived with the warmer water. Since this usually occurred around the Christmas season, they called the phenomenon El Niño, which means "the baby boy" in Spanish, in honor of the Christ child. La Niña, the opposite cycle of El Niño, means "the baby girl."

What are ice core samples and why are they important?

An ice core sample is a thick column of ice, sometimes hundreds of feet long, that is produced by drilling a circular pipe-like device into thick ice and then pulling out the cylindrical piece. Ice core samples from places like Greenland and Antarctica provide scientists with important clues about past climates. Air trapped in the ice remains there for thousands of years, so when scientists collect ice cores they can analyze the

Climactic changes are making life in places like Ethiopia more difficult. A warming planet means that deserts are expanding, making water resources more scarce.

Climactic changes are making life in places like Ethiopia more difficult. A warming planet means that deserts are expanding, making water resources more scarce.

air to determine the composition of the atmosphere at the time the ice was formed. Sediments and tiny bugs are also found in the ice and provide additional clues to the state of the natural world at the time the ice was deposited.

What is continentality?

Areas of a continent that are distant from an ocean (such as the central United States) experience greater extremes in temperature than do places that are closer to an ocean. These inland areas experience continentality. It might be very hot during the summer, but it can also get very cold in winter. Areas close to oceans experience moderating effects from the ocean that reduce the range in temperatures.

What are the horse latitudes?

These high-pressure regions, more formally known as subtropic highs, are warm and don't have much wind. Legend has it that the lack of wind sometimes caused sailors of the sixteenth and seventeenth centuries to throw their horses overboard in an effort to conserve water on board. That's how the region, centered around 30° latitude, got its name.

How does land turn into desert?

The process known as desertification is complicated and results from such activities as overgrazing, inefficient irrigation systems, and deforestation. It is most widespread in the Sahel region of Africa, a strip of land along the southern margin of the Sahara desert. The Sahara grows larger because of desertification. Desertification can be reversed by changing agricultural practices and by replanting forests.

 
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