To say that there are different types of clouds may strike some readers as a little odd. Clouds come in varieties? Preposterous! They're just a bunch of big, white and gray fuzzy things in the sky. Case closed.
Or perhaps not at all. Indeed, clouds are a great deal more complex and varied than they seem at first glance. Because they can appear at a variety of different altitudes and in different concentrations, clouds are quite narrowly stratified. There are quite a few different divisions of clouds hanging in the sky at this very moment, and if you want some help in figuring out what's coming up weather-wise, paying attention to their makeup is rather important.
The first element in deciding a cloud's classification is determining where it is in the sky. Clouds fall into four easy categories depending on their altitude: low, middle, high and vertical. Which area the cloud belongs in depends on the elevation of its base in the troposphere.
- Low clouds are those that range from ground level (fog, basically) to roughly 6,500 feet. Low clouds are often the densest of the lot and cover the sky more often, and are responsible for more precipitation as the water droplets cause the cloud to descend in the sky. As a result these clouds are almost always composed of water droplets rather than ice crystals, though there may be crystals at their peaks.
- Middle clouds are those that appear above 6,500 feet to below roughly 20,000 feet. These clouds blanket the sky similarly to low clouds, and are often heralds of rain or storms more than the causes of either (though some may do the job on their own). These clouds usually contribute to drab, gray days.
- High clouds are those that typically appear above 20,000 feet, and usually do so in puffy, wispy concentrations that look like cotton balls. They're so high in the sky that they are composed exclusively of ice crystals, and will sometimes contribute to hail or snow fall.
- Vertical clouds are those that, thanks to updrafts, extend and expand through the various levels and are vertically massive. They often sport dark gray bases and light caps. Cumulonimbus clouds, typically associated with thunderstorms, are typical vertical clouds.
These classifications are not enough on their own, however, as clouds at these elevations can come in a variety of different sizes and shapes. Consequently their names are often a combination of four different elements to help describe their appearance from the ground.
- Cirrus clouds appear to be small, tufted wisps, and show up most often at high altitudes. They're known as horse's hair clouds, informally.
- Cumulus clouds appear as large heaps in the sky, either appearing on their own or in clusters. They look a little like heaps of mashed potatoes.
- Stratus clouds appear as a long, unbroken layer of streaks that seem rather like mist or haze rather than hundreds of separate clouds.
- Nimbus clouds are usually dark at the bottom, and are associated with precipitation, most commonly rain.
- In addition to these, clouds sometimes receive the alto- prefix to determine if they are middle clouds. This is a consequence of being found in the middle of the troposphere more than any physical makeup.
Combining these terms determines what kind of cloud you're looking at. Cumulonimbus clouds, for example, are massive heaps that come bearing rain. Altocumulus clouds are lumpy clouds appearing in the middle of the troposphere. Cirrostratus clouds are those that appear as long, wispy lines in the highest altitudes of the troposphere.
Beyond this, identifying different types of clouds is a matter of looking and comparing with what others have seen. With enough practice you'll easily get the hang of IDing different cloud formations and, once that's done, discovering what each one brings with it - for just as clouds bring with them bad weather, they also warn that said weather is coming in the first place.