The extreme weather in the USA is so severe that even the weather satellites do not understand what

[Elderberry]

The Earth Chronicles February 20, 2021

The extreme weather in the USA is so severe that even the weather satellites do not understand what is happening

A violent winter storm in the southern United States caused such extreme cold that it confused the weather satellites tracking the situation.

On Tuesday, cold air approaching south of the Arctic froze the earth so much that one monitoring satellite mistook the earth for cloud tops, which are usually much colder than surface temperatures. This phenomenon was first pointed out by Washington Post meteorologist Matthew Capucci.

The satellite in question, called GOES-East, uses infrared sensors to measure temperatures at the top of the clouds and plot them. Clouds are usually colder than the surface of the earth. The satellite’s algorithms use this assumption to determine cloud cover from space even at night.

In Texas and on the plains, the extreme cold causes the earth temperature to range from zero to minus -10 [degrees Celsius]. ” This is 32 to 14 degrees Fahrenheit. The average temperature in Texas over the past five years has been 48 degrees Fahrenheit, according to a soil temperature map.

The satellite’s algorithm then got confused and mistook the temperature of the earth for clouds, marking them with blue and magenta, the colors usually reserved for clouds.

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[jmyrlefuller]

That happens pretty much every year up in the northeast. You'll see color enhanced images showing cloud cover over huge swaths, but it is in fact picking up the surface of the cold ground.

Infrared satellites work on the premise of our atmosphere being colder as altitude rises. Infrared brightness in certain parts of the electromagnetic spectrum correlates well with temperatures (the same principle behind thermal imaging, and also why you can use infrared cameras at night). So if you have an idea of what the temperature profile of the atmosphere is (that's what weather balloons are for), you can use an infrared satellite image to guess the heights of the clouds.

The problem in the winter is that most of the images you see are raw data: they don't calibrate it to the atmosphere, only spit out the infrared values and process them through a fixed color template. So if the surface temperature gets too cold, the infrared image will pick up a temperature that resembles a high cloud, and the color template will paint it accordingly.

It's neither severe nor extreme.