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Matt's World of Weather - Mysterious Cloud Photo

Besides taking on shapes such as a rabbit, a dragon, or even a rabbit flying on a dragon, clouds are often noticed when the weather is bad but quickly forgotten when it’s warm and quiet. I wanted to take some time and go beyond our imaginations and explain some of the science behind our friends in the blue horizon. If you would like, click the World of Weather video to get started.

Canal Clouds:
The first picture is a classic example of a Canal Cloud and was likely formed from the passing of an airplane or jet. This phenomenon aside, we have all been witness to this type of cloud formation. By itself and in the right conditions, the exhaust of a jet often takes on a linear, white tail, known as a contrail. Interestingly, like all clouds, a contrail can serve a meteorological purpose and identify aspects of the atmosphere without actually having to measuring it. For example, a contrail will only form in temperatures that are below -40°F. By spotting a contrail, you now know the temperature profile of that section of the atmosphere (No need to put on the winter coat for this measurement, the contrail does it for us). Moving on, clouds in general are very receptive to small changes in the atmosphere and it’s this characteristic that makes them so helpful in forecasting. In the case of a Canal Cloud it was an airplane that resulted in our phenomenon, but even smaller objects, like the introduction of just one ice crystal, can produce a stunning cloud structure as well…

Hole-Punch-Clouds:
The picture from the National Weather Service is called a Hole-Punch-Cloud. The process only requires a few ice crystals to begin a domino-effect that leaves a “hole” in the sky. In reference to the picture, the reason there is a lot blue in between the wispy clouds and the checkerboard clouds is because of the amount of moisture needed to create this phenomenon. Generally a thirsty ice crystal will require more moisture to make the water/ice transition. Basically one ice crystal will need, let’s just say, five supercooled water droplets to form. Thus, the wispy clouds eventually stop forming and take up a lot less space than the surrounding altocumulus clouds. The Hole-Punch-Cloud isn’t as common as the Canal Cloud and sometimes this cloud will even spark reports of flurries beneath the structure.

Cloud Physics:
The field of cloud physics is very interesting, but relies heavily on a strong math and physics background. In fact, studying clouds will take you beyond a four-year college degree. It is often a requirement that graduate students take a semester long course dealing with just clouds and the physics involved in their formation. Consequently, the intense classes can have a damaging affect on ones imagination for students no longer see rabbits in the clouds, rather, they see equations. For those who really want to dive deep into cloud physics, here is a sample:

http://journals.ametsoc.org/doi/pdf/10.1175/1520-0493(2000)128%3C0229%3AANCPPI%3E2.0.CO%3B2


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