What Goes Up - Must Come Down

This is an example of what rain looks like as it falls from a nearby shower. This is a rain shaft, a column of raindrops falling to earth. The shower was located near Ackley, just north of Highway 20 in northern Iowa. The cloud base is plainly visible except where the rain is pouring out of the storm. The rain falling from a large cumulus congestus cloud had not reached the thunderstorm stage of development. The shower rained itself out before it could get larger.

Notice the small cumulus in the lower right portion of the photo and also in the lower left. They have much weaker updrafts but may become larger during the heat of the afternoon. The shower’s thick cloud base had distinct rolls and a sharp demarcation between the cloud and drier air below.

What goes up and must come down? Water falling from this shower evaporated at some unknown location and may have traveled hundreds of miles before rising into the cloud base and condensing into cloud droplets. When the droplets became large enough they were too heavy for the shower updraft to support - they fell to earth. The rain is the beginning of the end for this shower because the rain cools the air and stops the updraft. Without the inflow of warm moist air the shower loses its source of energy.

Other showers formed throughout the afternoon on this warm humid Iowa day and they all went through the same life cycle. It was the water that evaporated, became cloud droplets, rain drops, and fell back to earth. The water went up and then came back down.