Clouds Can Help You Forecast the Weather

Weather Talk
Thursday, January 16, 2014 - 11:54am

The Type of Cloud Can Very Often Determine What Kind of Weather Is on the Way

I think I am going to start my own group of “Cloud Gazers”. Not only is looking at and analyzing clouds fun and relaxing but it can also help you predict if a storm is headed your way or what type of weather pattern may be in the near future. There are four basic groups of clouds, high, mid level, low level and vertically developing clouds.

To find out how clouds form, please read yesterday’s “Weather Talk”;
“Hey! That Cloud Looks like Grandpa!”

All cloud types have Latin based names. This table from my college meteorology text book, “Meteorology Today”, C. Donald Ahrens, 1994

Latin Root Translation Example
cumulus heap fair weather cumulus
stratus layer altostratus
cirrus curl of hair cirrus
nimbus rain cumulonimbus

The prefix of the Latin name will indicate the height level. Cloud names starting with “cirr-“ like cirrus indicates high level clouds and the prefix “alto-“ such as altocumulus are clouds located at the mid levels.

High Level Clouds- cloud bases above 16,000 feet to 43,000 ft in the temperate zones. These clouds are made up of almost primarily ice crystals and are thin.

Photo: Chuck DeBroder-Cirrus

Cirrus- These are the most common type of high clouds, white, wispy, feather like ice crystal clouds blown by high winds that look like paint brush strokes. They are called “horse or mare tails” because the feathery patch as the appearance of a tail.

FORECAST- The main, prevailing upper level winds usually carry cirrus clouds from west to east and generally indicate fair and nice weather.

Photo: Chuck DeBroder-Cirrostratus

Cirrostratus- These clouds are a thin to sometimes thick layer or sheet of high level ice crystals. These clouds are relatively see through or transparent even if can cover the whole sky and sometime they are several thousand feet thick.
They can be so thin on occasion that the only sign of their presence is given by an observed halo around the sun or moon. Halos result from the refraction or bending of light by the ice crystals in the clouds.

FORECAST-Cirrostratus clouds, however, tend to thicken as a warm front approaches, signifying an increased production of ice crystals. Because of this the halo around the sun or moon slowly disappears. The give the sky a glary, white appearance and often they form ahead of an oncoming storm. This could mean rain is in the not so distant future.

Photo: Chuck DeBroder-Cirrocumulus

Cirrocumulus- appears in small, rounded puffs or “cloudlets” alone or in long rows. This rippling distinguishes them from the wispy cirrus or sheet like cirrostratus. Often, cirrocumulus covers just a small section of the sky.
They appear most of the time white, sometimes grey. These clouds make for amazing sunsets and sunrises as they scatter the red, yellow, orange and violet light!

FORECAST- The small ripples in the cloudlets of cirrocumulus look like fish scales which is why the expression “mackerel sky” came to be. There is an old folk saying “mackerel sky, a storm is nigh”. Cirrocumulus seen during the cold season or winter and indicate fair, but cold weather.
Mid Level Clouds-These clouds have cloud base of 6500 to 23,000 ft in the temperate regions. These clouds are mainly made up of water droplets and when it is cold enough, some ice crystals.

Photo: Chuck DeBroder-Altostratus

Altostratus- An altostratus cloud usually covers the whole sky and has a gray or bluish-gray hue. The sun or moon may appear “watery” or “fuzzy” shining through an altostratus cloud.
FORECAST-An altostratus cloud usually forms ahead of storms with continuous rain or snow. On occasion, rain will fall from an altostratus cloud. If the rain hits the ground, then the cloud changes its classification as a nimbostratus cloud.

Photo: Courtesy of UCAR Digital Image Library

Altocumulus-these clouds a have a grey, puffy masses that sometime have parallel waves or bands. They are grayish-white with one part of the cloud darker than the other, which is what differentiates them from cirrus clouds. Altocumulus clouds usually form in groups and can be almost a mile thick, most of the time larger than cirrocumulus.
FORECAST- Altocumulus clouds are often called “little castles” indicating the presence of rising air. If you see altocumulus clouds on a warm humid morning, then expect thunderstorms by late afternoon. Altostratus clouds often form ahead of storms having widespread or continuous precipitation.

Low Clouds- have cloud bases 6500 ft. or lower and composed of all water droplets, most of the time. During the cold or winter season they may also consist of some ice crystals and snow.

Photo: Chuck DeBroder-Stratus

Stratus-They are uniformly grayish in color and can cover most or all of the sky. Stratus clouds can look like a fog that doesn't reach the ground. Actually when fog lifts it can often result in a deck of stratus clouds. This is a common cloud during the summer months over both the Atlantic and Pacific coasts.
FORECAST- Normally no precipitation falls from the stratus clouds, but sometimes they produce a light mist or drizzle.

Photo: Credit Carlye Calvin/UCAR

Stratocumulus-These clouds are low, with rounded lumps, light to dark gray and often appear in rows. You can see blue sky in between the lumps most of the time, depending on how far apart they are spread out.
FORECAST- There is only light precipitation, generally in the form of drizzle that happens with stratocumulus clouds. The rounded masses in a stratocumulus are usually twice as big as those in altocumulus clouds.

Photo: Chuck DeBroder-Nimbostratus

Nimbostratus- are dark grey clouds that have a shredded or ragged base that have a “wet look” that usually is because most of the time they are producing falling rain or snow. Visibility is poor below the layer of nimbostratus because the rain evaporates and saturates the air, producing of clouds or fog just below them. The nimbostratus clouds travel rather quickly with the wind which creates their shredded or ragged appearance.
FORECAST- Rain or snow will happen shortly or most of the time it is already occurring. Rain evaporated fog may also reduce visibility.

Vertical Developing Clouds

Photo: Chuck DeBroder-Cumulus

Cumulus- This is probably the most familiar type of cloud to everyone. These clouds appear as puffy white or light gray clouds that look like floating cotton balls. Cumulus clouds have sharp outlines and a flat base. Cumulus clouds generally have a base height of less that a mile (1000m) and are about little over a mile and a half wide width (1km) on average.
They have of the forms of towers, cauliflower or cotton.

FORECAST- Cumulus clouds can be associated with good or bad weather. Cumulus humilis clouds are associated with fair weather. Cumulus congestus clouds are usually associated with bad weather. Their tops look like cauliflower heads and mean that light to heavy showers can occur.

Photo: Chuck DeBroder-Cumulonimbus

Cumulonimbus- These clouds are dark, massive thunderstorm clouds sometimes can have a base of only 1000ft (300m) above the ground and may extend to 50,000 ft(15,000)m) or higher well above the tropopause. At this height, high winds will flatten the top of the cloud out into an anvil-like shape. These clouds have violent, powerful up and down drafts. , which can range from 50 mph (45knots) to over 100 mph (87 knots)! The warmer, lower part of the cloud is made up of water droplets towards the top the all turn into ice crystals and then large balls of ice or hail.
FORECAST- These giant thunderheads may contain all of the varieties of precipitation, large raindrops, hail, and even snowflakes and snow pellets depending on the time of year. Lightning, thunder and tornadoes are all produced by cumulonimbus.

In future “Weather Talk” blogs I will describe the other miscellaneous other varieties of clouds. To learn more about Foehn or Föhn Clouds check out my first “Weather Talk”; "Foehn" Clouds Over The Franklin's
Also to find out about our “brown cloud” read my “Weather Talk”:
Our Smoky, Brown Haze Is Enhanced By Winter Weather

Now we can look at the sky, figure out the types of clouds and have a better idea what kind of weather we can expect. I still think a “cloud gazing” group is a good idea. Let me know if you are interested and I hope you have many days of happy cloud watching!

Chuck DeBroder, Chief Meteorologist
KTSM, NewsChannel 9, NBC, El Paso, TX Chuck DeBroder NC9 @wxchuckNC9

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