Fun with Science Club®


			How do the ocean and atmosphere interact? Sharon Sample 03.13.01 Differences in the heating and cooling rates of land and ocean affect air circulation. Land and water temperatures rise and fall at different rates because land absorbs and loses heat faster than water does. During the day, hot air rises and is replaced by cooler air. This small-scale circulation is called a sea breeze, and usually starts three or four hours after sunrise, reaching its peak by early afternoon. At night, the land is cooler than the water because the land has given up its heat to the atmosphere. The cool air flows over the warmer water and rises as it is warmed. This circulation is called a land breeze, and usually starts to form in the late evening. It reaches its peak intensity near sunrise. Without the Earth's atmosphere, our planet would become extremely cold and barren of life. The atmosphere consists of nitrogen (about 70 percent) and oxygen (about 20 percent). The other ten percent consists mostly of carbon dioxide, water vapor, and several "trace" gases such as neon and argon. Like the glass roof and walls of a greenhouse, the Earth's atmosphere keeps its surface much warmer than it would be without the "greenhouse effect." How? Energy from the sun arrives as short-wavelength radiation (light), while the Earth emits long-wavelengeh (infrared) energy back into space. The hotter an object is, the shorter the wavelength of the radiation it emits. The short-wavelength sunlight easily penetrates the atmosphere and warms the Earth. However some of the long-wavelength energy emitted from the Earth is absorbed by the atmosphere before it escapes into space. Carbon dioxide, water vapor and other gases in the atmosphere are responsible for absorbing escaping long-wavelength energy. Thus, the Earth keeps some of the heat that would otherwise have been lost to space. The concentration of carbon dioxide in the atmosphere has changed in the past hundred years. Before the Industrial Revolution, carbon dioxide levels stayed nearly stable for thousands of years. Since human beings developed a fossil-fuel- based global economy and lifestyle, the amount of atmospheric carbon dioxide has increased dramatically. This increase means that less long- wavelength energy emitted from the Earth can escape to space. Many scientists believe this can lead to a gradual warming of the Earth, but others believe that different factors counteract this warming effect. For example, cloud cover reflects sunlight before it ever reaches the Earth, thus reducing the amount of sunlight that reaches the Earth's surface. Studying these processes is difficult, because they are complicated. Ocean color information provides one of the many tools scientists use to try to find what changes are occurring, and how they may affect us.


			National Atmospherica and Space Administration (NASA) Earth Science Enterprise kids.earth.nasa.gov