Ask Dr. Science

Mark Twain wrote in "Life on the Mississippi" that when he could look at a beautiful sunset on the great river, yet see nothing but the snags and sandbars in the water, he knew it was time to leave steamboat piloting and head West.

I'm not at that point yet, so it's still fun to put the scientist goggles on and look at the natural world....

My co-workers write the following about this picture:

1.) This is way cool.
2.) VERY cool! Marc, why does it do that??
1.) I think there is heat coming off the drill rig and the ceiling is so low that it is blowing a hole in it. Maybe???
2.) Either heat or turbulence, or maybe both, is my guess too.
3.) Only a couple of engineers would have this kind of discussion ;-)

I write:

It looks as if the clouds are altostratus and are actually miles above the ground. The hole appeared in the cloud deck and the clever photographer maneuvered themselves so that the top of the drilling rig pointed at the hole's center.

Regarding why the hole would appear, most of these clouds are likely made up of supercooled water droplets, meaning their temperature is below freezing. In order for water droplets to freeze, ice nuclei have to make contact with the droplets. In a big pool of water, like a pond, water will freeze at the freezing point, since some ice nucleus is almost always present somewhere in the pool, but if you finely-divide the water into tiny droplets, even if you dramatically lower the temperature, the water droplets remain water, because there isn't a ice nucleus available in each droplet. Only if temperatures are -40 degrees, or lower (deg F or deg C), will all the water droplets freeze without ice nuclei needing to be present.

Ice nuclei are not very common in the atmosphere, so clouds at -20 degrees or -30 degrees can exist for hours or days without freezing. Some materials, like leaf litter, make good ice nuclei, but leaf litter is uncommon high in the atmosphere. Probably what happened was, several hours before the photo was taken, a plane flew through the cloud deck, and scattered some particulate material, perhaps exhaust particles, or even dirt, but adequate to serve as ice nuclei. New ice crystals grew at the expense of the supercooled droplets (since the saturation vapor pressure of ice is lower than that of water) and slowly snowed out, leaving a nice, circular hole in the cloud deck.

Indeed, just to the left of the tip of the drilling rig, you can see the hint of an optical phenomenon, a "sundog", the brightest part of an incomplete halo, indicating that ice is present in the cloud deck in the hole, but nowhere else.