A cool breeze sweeps through the summer air after a warm day, stirring the trees and playing with my hair as I watch the distant sky turn that beautiful deep blue color the sky always becomes right before it rains. There is a rumble of distant thunder, the musty smell of rain, a flash of lightning coming closer, and finally I feel an icy droplet hit my head. I just stand there for a few minutes as the rain drops begin to fall heavier and more frequently, captivated by the wonder and beauty of the storm. Eventually, I come to the realization that I’m getting a little damp and the last lightning strike I saw seemed pretty close, and decide to retreat indoors. Storms are an incredible reminder of the power – and mercy – of God.
For the last few weeks, we have been exploring clouds and some basic cloud classification. Hopefully these topics didn’t get too dry for you (after all, clouds are made of water – they couldn’t possibly be a dry topic). This week, we will look into some of the amazing features that can be seen on our big storm clouds, which are cumulonimbus clouds, as you may remember from last week.
If you see a big cumulonimbus formation from a distance, you will probably notice that the biggest part of the storm cloud is much wider at the top and bottom than it is in the middle. This phenomenon is a supplementary feature that is only formed on cumulonimbus clouds and is often casually called an anvil (because the shape looks just like an anvil), or formally classified as “incus”(see picture below). The cloud formation flattens out at the top because it grew to a higher layer in the atmosphere where clouds don’t grow as well. Another thing you might notice at the peak of a tall pile of clouds is a smooth, transparent cap sitting on top of it, called “pileus” (literally from the Latin word for “cap”). Pileus forms on top as a cumulonimbus (or cumulus) cloud encounters a humid layer in the air. You know you have a strong storm if the cumulonimbus cloud bursts through the pileus .
From this distance, you might also be able to see a shaft of rain coming down from your storm cloud. If the rain shaft touches the ground, we call it “praecipitatio” but if it doesn’t touch the ground, we call it “virga” instead (see pictures below). If your storm gets a little closer, look above your head because you might see ominous bulges, called “mammatus” clouds, hanging above your head.
“ . . . Who maketh the clouds His chariot: Who walketh upon the wings of the wind” Psalm 104:3
