A Red Billowing Thunderhead

17 July 2013

In a clear sky with some stars and a smattering of alto (mid-level) clouds, the half-moon tonight shone bright and whitish-clear.  

In the distant western sky, there was a huge billowing cloud of at least 6-storeys high. At first glance, it appeared as if a house was on fire. But the ominous red billow stood unchanged for more than half an hour with no visible  flickering light in the horizon.

This is a thunderhead - a towering cumulus cloud.

Rather than spreading out in bands at a fairly narrow range of elevations, like other clouds, cumulus and cumulonimbus clouds rise to dramatic heights, sometimes well above the level of transcontinental jetliner flights.

Cumulus clouds are fair-weather clouds. When they get big enough to produce thunderstorms, they are called cumulonimbus, or thunderheads. These clouds are formed by upwelling plumes of hot air, which produce visible turbulence on their upper surfaces, making them look as though they are boiling. 

The convective airmass is  highly unstable. Just as it takes heat to evaporate water from the surface of the Earth, heat is released when water condenses to form clouds. In thunderheads, this energy can produce short-lived hail, damaging winds, lightning, torrential rain, and sometimes tornadoes. The top of the cloud points in the direction the weather is moving towards.

True enough, this is NEA's weather prediction for the next 12 hours:

More photos are available on Merlion Wayfarer Goes Green's Picasa at :
Natural Phenomena - Clouds and Natural Phenomena - The Moon