How do we study the ATMOSPHERE?
There are many ways scientists can study the atmosphere. These range from looking at a simple thermometer to analyzing data from a spacecraft in orbit.
Weather Stations: To study the atmosphere, we need to sample it at many places. This is because the atmosphere can change quite a bit over only a few kilometers. Temperature, pressure, and air moisture can all vary a great deal in a short distance. Because of this, most cities and towns have their own weather stations. Scientists can then look at information gathered across the country and around the world.
Weather Radar: But a weather station provides information for one isolated point in an area. Scientists who want to get a continuous view of the weather need to use other devices. One such device is radar. Just like airports use radar to track airplanes, scientists can use radar to track weather. These pictures are of a radar station. The radar dish itself is housed inside a dome, which protects it. The dome is made out of a material that the radar can see through, so it doesn't interfere with the radar signal. The radar dish rotates in a circle, looking at the weather in all directions.
Weather Balloons: Just taking measurements at the surface, however, is not enough. The atmosphere is many tens of km high, and all of it needs to be sampled for scientists to understand it better. Common methods include using weather balloons and sounding rockets. These devices can reach a very high altitude, taking measurements all the way up. This information can then be automatically radioed to a weather station or retrieved when the balloon or rocket falls back to the ground. Weather balloons are launched twice a day from a network of sites across the country. This provides a continuous set of information at regular times and locations.
Satellites: Even balloons and rockets have their shortcomings. While they gather lots of information, the information itself is relatively sparse. It would take many thousands of weather balloons to provide a complete data set, and launching these would be very expensive and time-consuming. Scientists want to know what's going on everywhere in the atmosphere immediately. The way that they can get close to this is by using satellites. Once a satellite is in orbit around the Earth, cameras and sensors on board can see what's occurring in all parts of the atmosphere. One satellite can replace thousands of weather stations. NASA has spacecraft that observe the Earth's atmosphere in many different wavelengths, and can observe water vapor, aerosols, and pollutants from space. (Learn more about NASA missions via this software or by going to http://science.nasa.gov)
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