A common Sense Approach to Safe Sailing
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Cumulonimbus Cloud Clouds
Clouds can easily be broken into four categories. These categories are high clouds, middle clouds, low clouds and clouds with vertical growth.
Clouds are also identified by shape. Cumulus refers to a "heap" of clouds. Stratus refers to clouds that are long and streaky. And nimbus refers to the shape of "rain" because we all know what rain looks like.
High clouds form at 16,000 - 43,000 feet. Basically, these are the clouds that you only encounter on the top of really high mountains or at the cruising altitude of a jet airplane. Due to the extreme conditions at which they form, they tend to be comprised primarily of ice crystals. High clouds do not block sunlight. High clouds include:
Cirrus clouds are white wispy clouds that stretch across the sky. By all accounts, cirrus clouds indicate fair weather in the immediate future. However, they can also be an indication of a change in weather patterns within the next 24 hours (most likely a change of pressure fronts).
By watching their movement and the direction in which the streaks are
pointed, you can get a sense of which direction the weather front is moving.
Cirrostratus tend to be sheet-like and cover the whole sky. You can usually
tend to see the sun or moon through them. Their presence usually indicates moist weather within the next 12 - 24 hours.
Cirrocumulus clouds tend to be large groupings of white streaks that are sometimes seemingly neatly aligned. In most climates these mean fair weather for the near future.
However, in the tropics, these clouds may indicate an approaching tropical storm or hurricane (depending on the season).
Middle clouds form at 6,500 to 23,000 feet. They are comprised of water, and, if cold enough, ice. Middle clouds often block sunlight, but not always.
Middle clouds consist of:
Altostratus are grey and/or blue clouds that cover the whole sky.
They tend to indicate a storm sometime in the very near future since they usually precede inclement weather.
Altocumulus are greyish-white clouds blanketing the entire sky. The tend to look like large fluffy sheets in which there is a lot of contrast between light and dark. Sun does not pass through them. If you see them in the morning, prepare for a thunderstorm in the afternoon.
Low clouds form below 6,500 feet. These clouds are the ones that like to hang-around just above tall buildings. These clouds tend to contain water, but can also be comprised of snow if the weather gets cold enough.
Low clouds block sunlight and can bring precipitation and wind.
Low clouds include:
Stratus are low-lying solid clouds that are often formed when fog lifts off the ground. They obviously look like an elevated fog. Often they bring drizzle or light snow.
Stratocumulus are low-lying bumpy and grey clouds. They do not bring precipitation. They also do not cover the entire sky and tend to come in rows and patches.
Nimbostratus is your standard rain cloud. It is a large flat sheet of grey cloud with a little bit of differentiation. If you see these, chances are it's raining outside.
Be aware there are clouds with vertical mobility. And last, but not least, are clouds with vertical growth which tend to have a base that hangs really low (5,000 feet) and a top that climbs really high (over 50,000 feet).
Clouds in this category include:
Cumulus clouds are your stereotypical white "cottonball" clouds. So long as the clouds remain low clumps floating across the sky, there will be fair weather. However, you need to keep an eye on these clouds because any vertical growth can indicate the start of a large storm.
Cumulonimbus are cumulus clouds that have grown vertically into an anvil-like shape. The anvil tends to point in the direction the storm is moving. These clouds bring most dangerous weather such as rain, lightning, hail and tornadoes.