Weer

Infrared satellite imagery

http://www.metoffice.gov.uk/satpics/latest_IR.html

These images come from satellites which remain above a fixed point on the Earth (i.e. they are "geostationary"). The infrared image shows the invisible infrared radiation emitted directly by cloud tops and land or ocean surfaces. The warmer an object is, the more intensely it emits radiation, thus allowing us to determine its temperature. These intensities can be converted into greyscale tones, with cooler temperatures showing as lighter tones and warmer as darker.

Lighter areas of cloud show where the cloud tops are cooler and therefore where weather features like fronts and shower clouds are. The advantage of infrared images is that they can be recorded 24 hours a day. However, low cloud, having similar temperatures to the underlying surface, are less easily discernable. Coast-lines and lines of latitude and longitude have been added to the images and they have been altered to northern polar stereographic projection.

The infrared images are updated every hour. It usually takes about 20 minutes for these images to be processed and be updated on the web site. The time shown on the image is in UTC.

How a satellite follows the movement of a hurricane 1. GOES-9 provides a constant vigil for weather conditions that can cause turmoil in our lives such as severe storms, hurricanes and tornadoes. To hover over the same area of Earth, GOES operates in a geosynchronous orbit 22,240 miles (35,790 km) above Earth. To help students understand this type of orbit, do the following activity: Have students work in pairs. Each group of students will need a flashlight and any kind of sticker. One student will represent Earth and the other the GOES satellite. The Earth students will put the sticker on one of their sleeves. The GOES student will hold the flashlight. The students can be challenged to calculate a scale for the distance the GOES student should stand from the Earth student. (It should be reasonable for the room where the activity is taking place.) Challenge the GOES students to keep the beam of the flashlight constantly on the sticker placed on the Earth student as the Earth student rotates on its axis. What direction should the “Earth” rotate? (counterclockwise) What direction should the “GOES” rotate? (counterclockwise) Is a geostationary orbit the best orbit for a weather satellite? Why? 2. Hurricanes are large storms that form in warm, moist, tropical air near the equator in summer and fall. Moisture from warm ocean water evaporates rapidly. Colder air from above moves down and pushes more warm air up. This is called convection; lighter, less dense, warm air rises when it meets dense, heavier, cooler air.