Sky Watch No.10

Today we have something a bit different... instead of the usual Sky Watch intro we thought we'd ask our very own Sky Watch 'Storm Chaser' (DEWDROP) to come up with a simple lessons on cloud formations... I'm sure there will be some who know all this already but it's always good to share knowledge and I'm convinced that these posting will be well received. So it's over to Dewdrop to start the ball rolling.

It is such an honor to be a part of such a wonderful, worldwide blogging phenomenon, as Sky Watch "Fridays". Through this wonderful event and all the phenomenal participants, we get the rare privilege of viewing skies all across the globe. Because of Sky Watch "Fridays", we have people everywhere looking at the sky and appreciating its beauty and wonder, what a magnificent work of art... I was honored when Tom, our wonderful co-host, asked me to prepare a Sky Watch series of lessons, helping everyone to learn a little something about what they are seeing. For lesson one, I have chosen a Cumulonimbus Cloud Structure, specifically Cumulonimbus Calvus.

Cumulonimbus calvus is a moderately tall cumulonimbus cloud which is capable of precipitation, but has not yet reached the height where it forms into a cumulonimbus capillatus (fibrous-top) or cumulonimbus incus (anvil-top). Cumulonimbus calvus develops from cumulus congestus, and its further development under auspicious conditions will result in cumulonimbus capillatus. This cloud consists mainly of water droplets. By definition of cumulonimbus cloud, at its top water droplets are transformed into ice crystals, but for cumulonimbus calvus content of ice crystals is small and freezing is in early stage, so cloud top still looks round and puffy. Cumulonimbus calvus is characterized by distinctive (between other types of cumulonimbus cloud) rounded shape and relatively sharp edges of its top area, unlike cumulonimbus incus or cumulonimbus capillatus, which have cirriform tops. Developing cumulonimbus calvus loses sharp outlines of the top as more water droplets transform into ice crystals. Strong updrafts may form pileus or thin vertical stripes protruding upwards out of the cloud. When upper part of the cloud freezes to greater extent and clearly visible cirriforms appears, cumulonimbus calvus turns into another species of Cumulonimbus .

This specific cloud produced a lovely light show with a full hour of cloud to cloud lightning filling its insides. Lesson prepared and photograph taken by Dewdrop (aka Jennifer Bilak)