November a Good Time to Watch for Clouds

by Kevin Strauss

As one of the cloudiest months of the year, November gives us a great
opportunity to watch the sky. Not only do clouds give the sky some color
(besides blue) and texture, they also tell us a lot about what weather we can
expect. As anyone taking a shower in a poorly ventilated bathroom can attest,
cloud formation requires just a few components. The most important component is
warm, moist air. But cloud formation also requires some dust and some cold air.
When warm moist air encounters dust and cold air, such as when warm surface air
rises into the sky or warm moist air reaches a cooler bathroom mirror, the water
vapor in the air "condenses" or changes form a gas to a liquid. Dust provides
the "nucleus" or starting point for condensation.

The clouds that we see throughout the year include three general categories:
cirrus clouds (Latin for "curls"), cumulous clouds (Latin for "heap") and
stratus clouds (Latin for "sheet"). Cirrus clouds are the high, wispy ice clouds
that we see on otherwise sunny days. They form 16,000-45,000 feet in the
atmosphere. They often indicate changing weather over the next few days and
precede stratus and other rain clouds. Cumulous clouds are the fluffy white
"cottonball" clouds that form on a sunny summer afternoon. They form from 1,000-
10,000 feet in the sky. If cumulous clouds stay as separate puffy clouds, that
usually indicates clear weather. If they begin bunching together they may form
a "thunderhead" and rain.

Stratus clouds are the flat, gray sheet-like clouds that often cover our sky in
November. The relatively stable air masses and lack of wind allow warmer, moist
air from the earth's surface to rise and condense (become a cloud) when it
strikes colder air. Stratus clouds can form anywhere from the earth's surface to
6,500 feet. When stratus clouds form near the ground to about 100 feet in the
air, we often call them "fog." Stratus clouds, if they get thicker and darker,
are a sign of precipitation. During November, this could come in the form of
rain or snow.

Experienced weather-watchers can predict local weather by just
knowing the wind direction and visible clouds. But for the less avid nature
observer, just remember that if you see clouds thickening and lowering, that is
a clear sign of rain. If the clouds seem to be breaking up, thinning and rising,
they the weather will be clearing. If the wind is blowing hard, get ready for a
change in weather. If the wind is still, our weather will stay the same for a
while.

Keep these things in mind as you get outside this month.

The Ely Timberjay