Collecting Weather Data     A great deal of weather data must be collected in order to forecast the weather. Examples of devices used to measure specific weather factors include thermometers and barometers. Thermometers measure temperature, and barometers measure air pressure. Measurements of barometric pressure are especially important for weather forecasting. A change in barometric pressure indicates that a change in weather is coming. If air pressure rises, clear weather can be expected. If air pressure falls, storms are likely. Barometric pressure data from a large area can be used to... Show more

Collecting Weather Data    
A great deal of weather data must be collected in order to forecast the weather. Examples of devices used to measure specific weather factors include thermometers and barometers. Thermometers measure temperature, and barometers measure air pressure. Measurements of barometric pressure are especially important for weather forecasting. A change in barometric pressure indicates that a change in weather is coming. If air pressure rises, clear weather can be expected. If air pressure falls, storms are likely. Barometric pressure data from a large area can be used to identify pressure systems, fronts, and other weather systems.    
Thermometers and barometers are found in weather stations. These are small collections of weather instruments, which may also include devices for measuring wind speed, wind direction, humidity, and precipitation. About 10,000 weather stations are located on land all over the world. In addition, weather stations are located on about 5  satellites, 700 buoys, 3000 aircraft, and 7300 ships. All of these weather stations constantly collect data on the condition of the atmosphere where they are located.    
Other devices that measure atmospheric conditions include radiosondes, weather radar, and weather satellites.    
- Radiosondes measure atmospheric characteristics such as temperature and air pressure as they travel through the atmosphere after being launched by a balloon or airplane. Radiosondes use radios to communicate the data they collect to a computer.    
- Weather radar sends out radio waves that bounce off precipitation in the atmosphere and then return to the radar device. Weather radar can sense many characteristics of precipitation, such as its location, intensity, and movement.    
- Weather satellites observe all wavelengths of electromagnetic radiation. They can create visible light images of features such as storms, clouds, fires, and smog. They can create infrared images of characteristics such as water and land temperatures.

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