Increasing Clouds

Autumn storms provide longer advance warning of their arrival than summer storms. The reason is the change in what causes storms during each season. Summer storms are smaller in horizontal extent than winter storms. They are also have much shorter life-spans. Winter storms are not as tall as summer storms. Summer storms develop quickly, winter storms take many hours or days to develop after they are identified.

NOTE: There is rarely a situation where storms are completely a “summer” or a “winter” storm. I am using that comparison to help readers understand that there are usually major differences in what causes storms to form and develop and how long they live during summer and winter.

Summer storms form and live off large amounts of warm air and moisture and flow patterns. Winter storms form and live off changes in temperature wind velocity with height.

The heat and moisture available in summer are the main driver of summer thunderstorms. Flow patterns determine the type of thunderstorm and severity. Winter storms depend on air flow vertically through the atmosphere. Differences in temperature, moisture, and flow patterns shape the intensity and type of storms. Those differences cause summer storms to be relatively small in size when compared to winter storms but summer storms are usually taller than winter storms. Winter storms sprawl over several states at once, sometimes influencing weather in one-third to one-half of the nation. Commercial airliners go around thunderstorms but can usually fly over winter storms.

Today was a good example of how the sky looks in winter compared to summer. On the prairie we can see storms coming for many miles so it is easy to change in cloud types when looking from horizon to horizon. The flat clouds of winter were on display. Below are several pictures of the sky this afternoon. From the top picture to the bottom the evolution of clouds indicated more of a winter than summer type storm was approaching. It is too bad the Sun went down because there would have been more to see.

Cirrus own the high altitudes. A commercial airliner flies between bands of cirrus in this photo looking south from Cedar Falls, Iowa. cirrus often mark a change in the weather if the clouds thicken and lower in time. Most cirrus are made entirely out of tiny ice crystals. Photo by Craig Johnson. Copyright 2018

Beautiful! These wave clouds reveal ripples in the upper level flow. These clouds were above 16,000 feet and in the Cirrus level. They are a form of Cirrocumulus and are likely made of water droplets and ice crystals.. Photo by Craig Johnson, copyright 2018

More waves. Gravity waves create these waves and are similar to waves in a stream. These ripples cause bumpy rides on aircraft. They occur in clear air - it is clouds that make them visible. Photo by Craig Johnson, copyright 2018

High clouds herald an approaching storm - especially when the clouds thicken and lower. The high clouds are forming to the west and moving east well in advance of the main storm. Photo by Craig Johnson at Cedar Falls, Iowa. Copyright 2018

Next up were MID LEVEL clouds - the puffy clouds in this photo are Altocumulus. They indicate a layer of moisture in an unstable layer at about 7.000 feet. Notice the wave pattern in the Altocumulus. These clouds show off summer (puffy) and winter (waves in bands) cloud types. The bands are parallel lines much like a series of waves seen in water. Photo by Craig Johnson. COPYRIGHT 2018

This shows a growing mid-Level cloud layer. As moisture and lift increase more clouds form, thicken, and lower. The entire process shows how clouds gradually increase and change type in advance of the approaching storm. Photo by Craig Johnson, copyright 2018