Interesting Visible Satellite Imagery

It’s been a nice day around here thanks to a broad area of high pressure centered just off the East Coast. There is a light south breeze blowing with temperatures in the 80s at mid-afternoon; the highest readings so far include:

Unofficial Highs as of 3:30 PM
84º in Florence and Moulton
83º in Madison
82º in Decatur and Huntsville
81º in Winchester
79º in Fort Payne, Scant City, and Scottsboro
78º in Toney and Cullman

The afternoon warmth comes courtesy of two things: a partly to mostly sunny sky and the southwesterly flow throughout the lower and middle atmosphere. The southwest flow just above the ground is pushing in warmer air from the west, and the solar energy is warming the ground at the same time; that accounts for the big leap in temperatures we have had today (and the continued warming through week’s end).

What brings nice weather to the Tennessee Valley brings wet weather to other places. In the Florida Peninsula, for example, the high off the East Coast is providing an easterly flow from the Atlantic, across the land between Orlando and Lake City, and back to the Gulf of Mexico. Since the wind is blowing from smooth ocean onto the land, convergence (faster winds blowing into an area where the wind is blowing more slowly) is creating clouds, showers and gravity waves. A gravity wave is any wave in which gravity is the restoring force; that’s a fancy, scientific way of saying that the wind hitting the Florida peninsula becomes turbulent and creates waves in the atmosphere that might look a little something like this:

Find out more about gravity waves here: theweatherprediction.com.

Those waves are invisible, but sometimes they do have a visible effect when they produce bands of clouds that seem to spread out from a single point. Watch the cloud bands move west from the Florida Coast out over the northern Gulf of Mexico. The bright white clouds over the land are producing showers; the narrow bands of cumulus clouds moving away from the coast are a product of moist air in that up and down environment caused by the atmospheric waves! Clouds are produced near the top of the wave crest where air is rising; the air is clear at the bottom where there is a sinking motion.

If you look closely at the bottom, you will see another impact of atmospheric waves. The narrow cloud bands moving north from the cluster of clouds at the bottom of the loop are most likely caused by either thunderstorm outflow or other thunderstorm-induced atmospheric waves!

It’s amazing what you can see the atmosphere doing even when the weather is relatively calm!

-Jason
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