Seeing snow from space and the science behind it

Seeing snow from space and the science behind it

(WMC) - Most of the southeast has seen snow at some point over the past few weeks. Most of us have seen it in person or through all the pictures on social media. But it can also be seen from space, usually from a visible satellite animation or snapshot.

There are two main types of satellite images; visible and infrared (IR).

IR or infrared satellite imagery is sort of a temperature map. The weather satellite detects heat energy in the infrared spectrum (infrared energy is invisible to the human eye.) The satellite image displays objects(whether clouds, water or land surfaces) based on the temperature of the object. Warm temperatures appear in dark shades. Cold temperatures appear in light shades.

Visible satellite pictures can only be viewed during the day, since clouds reflect the light from the sun. On these images, clouds show up as white, the ground is normally grey, and water is dark.

Check out the visible satellite image below from noon on Wednesday, January 17 from the Suomi NPP VIRRS imager in true color. I've highlighted a few things seen on this one image. One of those is snow on the ground.

How does snow show up on a visible satellite? In winter, the snow-covered ground will be white, which can make distinguishing clouds more difficult. To help differentiate between clouds and snow, looping pictures can be helpful; clouds will move while the snow won't.

Snow-covered ground can also be identified by looking for terrain features, such as rivers or lakes. Rivers will remain dark in the imagery as long as they are not frozen.

You can easily see the rivers in northeast Arkansas and especially the Mississippi River. In the animated loop of this, the only white areas that are moving are the cloud areas. The snow-covered area that looks like clouds remain still.

Always fun to dig a little deeper into the science of weather.

Spencer Denton
WMC Action News 5 Meteorologist
First Alert Storm Tracking Team
Meteorologist Spencer Denton
Twitter: @spencerstorm5

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