Jester’s Hat Anvil Cloud

January 15, 2011

Photographer: Christine Churchill
Summary Author: Christine Churchill; Jim Foster

The photo above shows an odd-shaped thunderhead illuminated by the setting Sun over the Mayacamas Mountains of northern California. On this November day conditions in the upper troposphere conspired to give the storm cloud the appearance of a jester’s hat. Flattening occurs when a storm’s growth is halted by a boundary layer most often the tropopause, which is the boundary between the troposphere and the stratosphere. The height of the tropopause varies from season to season. In the mid-latitudes and tropics, cloud tops may shoot up in excess of 60,000 feet (18,300 m) during midsummer. However, by late fall, when this photo was taken, the surface and lower atmosphere are considerably colder, and the tropopause is typically thousands of feet lower. Photo taken in November of 2009.

Photo details: Camera Maker: SONY; Camera Model: DSLR-A100; Focal Length: 40.0mm (35mm equivalent: 60mm); Aperture: f/20.0; Exposure Time: 0.125 s (1/8); ISO equiv: 200; Exposure Bias: none; Metering Mode: Spot; Exposure: shutter priority (semi-auto); White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB; GPS Coordinate: undefined, undefined.