Summer Pileus Cloud Over Central New York State

March 28, 2012

PileusNY_DSC00308 (2)

Photographer: Mike Clark
Summary Author: Mike Clark; Jim Foster

I spotted this fuzzy looking cap cloud after a series of thunderstorms passed through central New York in August 2011. The Sun was low in the western sky and highlighted the "skullcap" growing above the cumulonimbus clouds to the southeast of my location. These pileus clouds may form as cumulus clouds rapidly build and ascend at velocities of 40 feet (about 12 m) per second or more. As these clouds rise, they force a mass of air ahead of them. When the air close to the mushrooming convective clouds is near saturation, additional lift from the fast-rising current causes the air column to become thoroughly saturated. The result is a smooth, rounded cloud, capping the clouds beneath it. Photo taken on August 12, 2011.

Photo details: Camera Maker: SONY; Camera Model: SLT-A55V; Focal Length: 55.0mm (35mm equivalent: 82mm); Aperture: f/5.6; Exposure Time: 0.010 s (1/100); ISO equiv: 100; Exposure Bias: none; Metering Mode: Matrix; Exposure: program (Auto); White Balance: Auto; Flash Fired: No (enforced); Orientation: Normal; Color Space: sRGB; Software: QuickTime 7.6.6.