Satellite images help predict patterns
It’s hard to believe we were basking in 80-degree sunshine just a week ago. Though September ended on a cold note, the month overall was much warmer and drier than normal. The .49 inches of rain that fell in Spokane was .25 inches below normal for the month. Coeur d’Alene came out even drier, with only .45 inches of rainfall in a month that averages 1.58 inches.
Though the current El Niño points to a warmer and drier than average October, we have definitely started the month on a cool, wet note. Average highs now are in the middle 60s and average lows have slipped into the upper 30s. Many areas have already experienced the first freeze of the season. Precipitation generally increases this month, with an average of 1.93 inches in Coeur d’Alene and 1.01 inches in Spokane.
As weather patterns shift during the fall and we see a more active storm pattern, one of the ways meteorologists will stay ahead of approaching storm systems is with the use of satellite imagery.
Meteorologists weren’t always able to get a bird’s-eye view of incoming storms. It wasn’t until 1960 that NASA launched the first successful weather satellite, TIROS-1 (Television Infrared Observation Satellite). Up until that time, surface observation reports were the only way to get information about incoming storms. Imagine a hurricane season in which there were no easy way to track these violent tropical storms as they barreled toward land. Such was the case during the deadliest hurricane on record, when in September 1900, 8,000 people died as a category 4 hurricane devastated Galveston, Texas. No one saw it coming.
These days, meteorologist can get a global view of weather patterns from outer space with both geostationary and polar orbiting satellites. The geostationary satellites, such as GOES-West and GOES-East (for Geostationary Operational Environmental Satellite), orbit the earth over the equator at an altitude of 22,240 miles. They are called geostationary because the satellite remains in a fixed position relative to the earth, taking pictures over the same area so that images can be put into a time-lapse or loop. The polar orbiting satellites, as their name implies, orbit the earth in a north/south path passing over both poles. These satellites orbit at a much lower altitude, about 530 miles, providing higher resolution pictures. Because of their movement, however, they only pass over a particular point in their orbit twice a day.
Weather satellites can collect a vast amount of information about our atmosphere, but what most people are familiar with are the images of the clouds. Visible imagery is acquired when the satellite snaps a picture from above, much like we would do with our own cameras. To get pictures of the clouds at night, however, different technology is used. Infrared images are produced when the satellite measures the temperature of the clouds (low clouds are warmer, high clouds colder) and computers process that information into the cloud images we see on TV.