Clouds of the Day - Altocumulus - Thursday, March 7, 2024

Moist air aloft is beginning to spread north into Iowa. The clouds below show the progression of cloud types into the area this morning. The individual cloud elements are rounded due to columns of rising air surrounded by areas of sinking motion. The cloud type is Altocumulus. Notice how the clouds are aligned in rows due to wave action in the air aloft.

Altocumulus aligned in rows like waves on the ocean or a lake. The air is undulating with clouds lined up along the crest of the waves and clear areas at the trough (bottom) of the waves.

Another photo with clouds revealing the waves.

T his is looking west at the leading edge of a large area of Altocumulus spreading north. North is to the right. The air is too dry to the right to allow clouds to form but the changed as the pattern shifted northward.

Closer look at the Altocumulus.

One more photo of very ‘healthy’ looking altocumulus.

Altostratus often creates a featureless gray sky - this is a classic example. The Sun’s disk is visible through the cloud behind the trees.

This day ended with a sheet of Altostratus spread over the sky. It had evolved from waves of Altocumulus in the morning to larger cells of round Altocumulus by early afternoon. This was due to a surge of warmer moist air invading a cool dry air mass from the south. The Altocumulus formed in waves as moist air encountered the drier air, which set the air into a wavy turbulent motion. As the air became mixed by the waves and the puffy Altocumulus cells, Altostratus formed in the more stable air mass. The upward motion was weaker and spread over a broader area as a cloud sheet.