Study Satellite Images for Weather
Studying a satellite images for weather means understanding satellite types and their properties. GOES (Geostationary Operational Environmental Satellites) and other satellites orbit the Earth at an altitude of 22,000 miles above the equator once every 24 hours. These satellites function by keeping pace exactly with the Earth's rotation. Because of the satellites synching with the earth's rotation, these satellites appear fixed above the same locations on Earth all day. Each geostationary satellite records several images every hour.
Instructions
1. Understand read infrared satellites. Look up a current satellite weather map on The Weather Channel (weather.com) or via the National Weather Service (noaa.gov). The colored images you see floating across the map are infrared (IR) satellite images. Stationary satellites record long-wave infrared radiation with wavelengths in the atmosphere emitted by cloud tops, land masses, oceans, ice and snow. Most things on Earth emit long-wave infrared radiation (warmer objects emit more than colder ones. Hence, the relative amounts of infrared radiation emitted by cloud tops, land, oceans and snow/ice give information about their relative temperatures.
2. Recognize visible satellite images. Visible satellites produce images humans can see with the naked eye. These satellites record visible light, sunlight that is reflected by clouds, land, oceans or snow and ice and into the satellite camera. Because visible image satellite record reflected light rather than emitted radiation, they tell how reflective an object is but do not indicate temperature. This type of satellite is useful for tracking a storm like a hurricane but not indicating its intensity or the temperature of the swirling cloud formation.
3. Learn where satellite images come from and how they can change. Satellites send images to the National Centers for Environmental Prediction (NCEP) in Washington, D.C. The images depict recorded infrared radiation (long waves) emitted from clouds, land, oceans, ice and snow.
4. Look for warm areas. Warm areas show up in black. Also, the darkest parts of the satellite image depict land or ocean surfaces, which are usually warmer.
5. Recognize cold areas. Cold areas show up as white. Objects (clouds, land and oceans) with intermediate temperatures show up in gray shades. The lightest parts of an infra-red image show high, cold clouds. For example, the tops of high, towering clouds are usually colder than land or oceans that would show up as "warm" and dark.
6. Compare infrared and visible images. Search the image for visible images like high and low clouds. These objects often appear equally bright because all clouds have similar reflective properties. Scan the image for fog images: fog and low clouds are often easy to see on visible images-they reflect much more light than oceans or land surfaces. Infrared images are more difficult to pick out on a map; fog and low clouds are often hard to distinguish from land or ocean areas because these features often all have similar temperatures. Choose a weather pattern to study-fog, snow, rain clouds. Follow its activity, noting temperature or visibility change. Note that visible satellite images can only track in the daytime, when the objects are visible. Infrared satellites, however, never stop emitting and picking up long-wave radiation and can track weather conditions day or night via temperatures.
Tags: land oceans, satellite images, infrared radiation, oceans snow, clouds land, clouds land oceans
