Hole Punch and Fallstreaks Over Paris

January 16, 2013

Hole Punch and Fall-streaks Over Paris

Photographer: Bertrand Kulik; Bertrand’s Web site
Summary Authors: Bertrand Kulik; Jim Foster

The photo above showing a yawning hole in an altostratus cloud deck was captured over Paris, France on December 29, 2012. This hole is referred to as a hole punch. Hole punches such as this are nearly always caused by aircraft passing through a thin cloud layer. They take shape when supercooled water droplets in the cloud are agitated as a plane enters and exits, causing the droplets to freeze instantly into ice crystals. As this occurs, latent heat is released. This warms the air and leads to evaporation of the part of the cloud deck not directly affected by the plane’s transit. Note the two wispy shafts within the hole – at right center. They result when ice crystals fall through the hole punch and are known as fallstreaks. The crystals fall through warmer and drier air and will sublimate before reaching the surface.

Photo Details: Camera Maker: Canon; Camera Model: Canon EOS 7D; Lens: EF100-400mm f/4.5-5.6L IS USM; Focal Length: 100.0mm; Aperture: f/13.0; Exposure Time: 0.0063 s (1/160); ISO equiv: 100; Software: Digital Photo Professional.