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Cumulonimbus Incus

Whenever I look up and spot a cumulonimbus cloud, I always stare for a few minutes longer
because to me, these clouds have a lot of character.

What with that unmistakable look of giant cotton candy in the sky, that has been pulled in all
directions thanks to a bunch of ravenous children.

Character no doubt, these clouds are also known as ‘thunderheads’. Spurred on by uneven pockets of convection rising from the earth’s surface, the moisture in the
air converts to water vapour carried by upward air currents, causing these clouds to rise several
km into the sky while causing thunder, lightening, heavy showers, hail or gusty winds at the
lower altitudes.

Next time you’re caught in a thunderstorm, look out of the window and wave to your dramatic
but friendly resident cumulonimbus!


But why am I going on about cotton candy clouds when all you see here is flat, linear cloudsrunning parallel to the ground?

Introducing cumulonimbus incus aka the anvil cloud.

Here is a diagram of my version of a mega cumulonimbus incus.



Cumulonimbus are massive moisture laden clouds that mean business or ‘a cumulus but turned to eleven’ according to Gavin Pretor Pinney, author of The Cloudspotters Guide.

Classified as high clouds, these often extend vertically for several kilometers into the sky. We were at cruising altitude when I took this photograph enroute to Colombo from Mumbai.

When the tops of these moisture laden clouds convert to ice crystals, due to altitude and temperatures in the atmosphere, they spread out horizontally forming a band across the sky that can be several kilometers long at times, giving it the characteristic anvil or incus shape that you see here.

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