Summer is winding down. It’s time to get out and enjoy the outdoors while most days are still warm and the weather fair.
Speaking of fair, if you’re planning a picnic, look for fair weather cumulus clouds– the technical term is “cumulus humulis,” or “humble cumulus.” These clouds often pop up during the late morning and afternoon, and if they remain flat with little vertical development, that means outdoor activities should proceed without the threat of rain.
Clouds are divided into three categories based on altitude. There are high clouds, mid-level clouds, and low-level clouds. High-level clouds are made of ice crystals. They are often thin and wispy and indicate fair weather. However, if a sheet of cirrus, called cirrostratus, forms, this can indicate precipitation within 12 to 24 hours.
Then, there are mid-level clouds, like altocumulus clouds. They form at 10- to 15,000 feet and are made of water droplets. When these clouds thicken and form a continuous sheet, rain is imminent.
Back to low-level clouds: when cumulus clouds build vertically and grow into towers, showers and even thunderstorms may erupt. A mature thunderstorm cloud is called a cumulonimbus.
There are also low clouds that are flat, called stratus. These clouds produce a continuous overcast. Upper Michigan residents get accustomed to seeing these clouds in fall and winter.
The greatest possible sunshine, with the least cloud cover, occurs in July when sunshine can be expected about 67% of the time on average. Possible sunshine begins decreasing late in summer and early fall and reaches a nadir in late fall and early winter when overcast skies can be expected most of the time on most days.
