Clouds of the Day - A Change of Seasons - Thursday, October 5, 2023

This morning these Altocumulus and Altostratus clouds were in the sky at sunrise. Rising motion in a southwesterly flow of air through the middle levels of the atmosphere and moisture were enough to reveal a wavy air flow that was impressed on the clouds.

A combination of Altocumulus and Altostratus clouds are visible in the photo. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

This is a wider view of the clouds shown in the photo to the left. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

A change of seasons is showing its hand today. The weather map at 1:00 p.m. CDT shows colder air sweeping southeastward from Canada across the Northern Plains to the Central Plains. There are two cold fronts associated with the change. The leading front extends from Michigan to Illinois to Oklahoma. The second much stronger front has reached Lake Superior and extends to Iowa, Kansas into Colorado and then along the Continental Divide through Wyoming and Montana into British Columbia.

The is a good example of how temperatures, dew points, and winds change behind a strong cold front. Cedar Rapids, Iowa report 77 degrees with a dew point of 46, but farther to the northwest Bismarck, North Dakota reported 53 degrees with a dew point of 39 and Rapid City, South Dakota reported a temperature of 61 with a dew point of only 27.

Northwest winds were increasing behind the front and surface barometric pressures were rising as the cold dense air mass and sinking motion spread to the southeast.

A high pressure area of Pacific origin was sprawled over the western United States while the western edge of a high pressure over the Atlantic Ocean was along the Eastern Seaboard. Low pressure with rain was organizing over Louisiana and Arkansas.

Map plotted by digital Atmosphere, software available at www.weathergraphics.com

Rather unusual cirrus are visible to the southeast this after around 1:00 p.m. Closeup photos are shown below. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

These Cirrus live op to their namesake. This clouds have a wave like texture that is characteristic of many cirrus clouds. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

These clouds are also hairlike. In the cold air aloft these ice crystal clouds look delicate against the blue background. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

Altocumulus floccus look like tufts of wool. In this photo the clouds are aligned is rows from the bottom to top of the photo. In between the rows the air is sinking and evaporating the clouds. Photo copyright by Craig Johnson, Weather Briefing LC October 2023

This is Another example of floccus. They form in the mid-levels between 6,500 and 20,000 feet above sea level - if the atmosphere becomes unstable due to an increase in temperature or moisture. Photo copyright by Craig Johnson, Weather Briefing LC October 2023