|Brrrr!!! It's cold "Up There"|
it was cold up "There". Pictured above is an infrared
satellite picture ( here is more
information on U.S. weather satellites) of the Eastern United States
taken 22 Feb 2001 at about 6 am. A sensor onboard the satellite measures
the infrared radiation (or temperature) of emitting surface. For
example, where there are clouds, the instrument measures the cloud top
temperature. And where skies are clear, the instrument measures the
ground temperature. And therein is the story of this picture.
Note the area of red on the image. Temperatures within the red area are at about -40F (or -40C -- they're equal at this temperature). (FYI -- the yellow areas are warmer; the purple areas colder.) There are two large "red" areas in this image. The first is "Up There" across a broad area of Quebec to the east of James and Hudson Bays. The second is "Up There" across much of the Mid-Atlantic states and Ohio. The interesting feature of this image -- the definition of "Up There". In Quebec, "Up There" refers to north, as in north of the United States. In Quebec, skies were clear at the time of this picture and the satellite was measuring -40F temperatures at ground level. In contrast, across the Mid-Atlantic states, "Up There" refers to the vertical, as in 30,000 feet above the ground. Here, the satellite was measuring cloud-top temperatures of -40F at 30,000 feet.
View the latest Eastern U.S. and Western U.S. IR satellite images.