Meteorologists use many tools to help them gather information about weather and climate. Some more familiar ones are thermometers (which measure air temperature), anemometers (which gauge wind speeds), and barometers (which provide information on air pressure). These instruments allow meteorologists to gather data about what is happening near Earth’s surface. Collecting data from other sources—and other parts of the atmosphere—helps to create a more descriptive picture of weather.

Weather satellites

Weather satellites are invaluable for viewing large weather systems on a worldwide scale. Satellites show cloud formations, large weather events (such as hurricanes), and other global weather systems. With satellites, forecasters can see weather across the whole globe: the oceans, continents, and poles.

Each weather satellite has two types of sensors. One is a visible light sensor called the “imager,” which works like a camera in space and helps gather information on cloud movements and patterns. This sensor can only be used during daylight hours, since it works by capturing reflected light to create images. Different surface features reflect light in distinctive ways, so they can be distinguished from each other in the images. Water reflects very little light, making it appear black on the satellite image. Land masses tend to appear as shades of gray, depending on their temperature and moisture.

The second sensor is called the “sounder.” It’s an infrared sensor that reads temperatures. The higher the temperature of an object, the more energy it emits. This sensor allows satellites to measure the amount of energy radiated by Earth’s surface, clouds, oceans, air, etc. Infrared sensors can be used at night, which makes them a helpful feature for forecasters, considering that the above-mentioned “imager” can only pick up data during daylight hours.

Doppler radar

Doppler radar is another essential meteorological tool. Radar works a little differently from satellite sensors. Where satellites utilize light or energy, radar measures reflected sound waves.

When sound waves are broadcast from a radar antenna, they may come into contact with objects in their path, such as dust particles or ice crystals. If they come into contact with an object that is moving away from the radar, the sound waves will be reflected back at a decreased frequency (fewer sound waves will be reflected back within a certain time period). If the object they come in contact with is moving toward the radar, the sound waves will be reflected back at an increased frequency. This effect was discovered in 1842 by Christian Doppler. Later, scientists applied Doppler’s principle to weather radar. Using Doppler radar, meteorologists can get a picture of precipitation that allows them to track a storm’s progress over time.

 

(adapted from source)