Hole Punch Cloud and Fallstreaks Over Sao Paulo, Brazil

September 09, 2014

MeireRuiz 2

Photographer: Meire Ruiz; Meire's Web site
Summary AuthorMeire Ruiz; Jim Foster

The photo above shows a hole punch and fallstreak as observed from almost directly below. It was taken from Itanhaem, Sao Paulo, Brazil, on September 5, 2014. A sky with a hole like this results when a shallow, mid-level cloud deck is penetrated by an aircraft of some kind. The supercooled water droplets in these clouds will freeze instantly when jostled by a jet or airplane. Heat of fusion (freezing of the supercooled droplets) warms the air and evaporates the thin cloud layer around the plane's entry point. The gauzy clouds toward the middle of the hole punch are called fallstreaks. Composed of ice crystals, not water droplets, they'll sublimate well before reaching the surface.

Photo details: Camera Model: Canon PowerShot SX40 HS; Focal Length: 4.3mm; Aperture: f/2.7; Exposure Time: 0.0010 s (1/1000); ISO equiv: 125.