By Jonny Lupsha, Wondrium Staff Writer
A rare case of extreme weather in Texas threw satellites for a loop. Some of them have even mistaken frozen ground in the Lone Star State for tops of clouds. Weather satellites are quite sophisticated, able to detect an incredible amount of detail.
Weather satellites have been a part of reporting on meteorology since the 1950s. Since that time, the United States has sent about 40 satellites into orbit intended for weather observation. Some of them are geostationary satellites, meaning they match the speed of the Earth’s rotation and stay above one location; others orbit Earth at their own speed.
After a sudden deep freeze that left dozens of Texans dead and millions without power, those satellites were so caught off-guard that one of them took the surface’s sudden low temperatures as a sign of cloud coverage, since cloud tops are usually far colder than the ground.
Weather satellites are far more complex than meets the eye. In his video series The Science of Extreme Weather, Professor Eric R. Snodgrass, Director of Undergraduate Studies for the Department of Atmospheric Sciences at The University of Illinois at Urbana-Champaign, explained more.
The Way It GOES
“The United States typically operates two geostationary weather satellites called the GOES satellites, which stands for Geostationary Operational Environmental Satellites,” Professor Snodgrass said. “The specific satellites are swapped out every 10 years or so, but there’s always a GOES-East and a GOES-West. Together, the two satellites observe from 20 degrees west to 165 degrees east longitude, providing full scans of the United States every 15 minutes, and full disc images every 30 minutes.”
Professor Snodgrass said that rapid scan technology allows each satellite to image a certain part of the world with “one-minute time resolution.” In other words, that’s one image every minute, which allows meteorologists to observe a storm system’s evolution frequently and with accurate imaging as recently as one minute in the past.
“Geostationary satellites excel in providing excellent spatial coverage and very high time resolution, but the greatest pitfalls of these images are spatial resolution and lack of color,” Professor Snodgrass said.
“Since the 1960s, low-Earth orbiting satellites operated by the US government have maintained spatial resolutions that are about two orders of magnitude better than the operational meteorological satellites,” Professor Snodgrass said. “The highest spatial resolution satellite data that has been public and made available for free since 1972 comes from the Landsat satellites, [whose] spatial resolution is just 10 meters.
“If the government has maintained this technological superiority, current satellites that are used for military reconnaissance are able to image the Earth with a spatial resolution of approximately one centimeter.”
At this resolution, he said, low-Earth orbiting satellites could easily detect someone’s hair color as well as the make and model of their car. These satellites are the reason that modern military wear camouflage with digital patterns.
“Next time you see US military personnel wearing modern camouflage, look very closely, with permission of course, at their clothing,” Professor Snodgrass said. “You will see that the the camouflage is pixelated, and that each color patch is a very, very small pixel of color. These clothes are designed to help keep our military hidden in these satellite images.”
Despite their razor-sharp image clarity, Earth-observing satellites can still get thrown off by the occasional incident of extreme weather.