Let’s take a closer look at the different types of clouds. What are they? In fact, clouds are formed when the water vapor evaporating from the earth’s surface rises up and meets the cool air of the high altitudes.
The warm air can contain water vapor as such, but the cold air does not have the capacity to hold that much water in the gas form. So the vapor condenses into small microscopic droplet. These droplets join together, and this is how a cloud is formed. Technically speaking, fog also is a cloud, but in layman’s eyes clouds are seen above the ground level, so we do not generally refer to fog as a cloud.
Depending on the shape and altitude, clouds are classified into different types. We add certain words like cumulo, alto, nimbo, cirro and strato to the names of the clouds. These words tell us what type they are. Basically there are three types of clouds – cirrus, cumulus and stratus. These names are suggestive of the shape of the clouds. Let us look at all the sub categories of the types of clouds.
As said earlier, fog is the cloud found on the lowest level. These are seen to be embracing the ground, and are composed of fine droplets of water. Fog is a kind of stratus cloud. Stratus clouds are light grey in color and cover the sky (or the ground in the case of fog) evenly. Most often they are found close to the ground, and they have the tendency to grow by bumping into each other.
At an altitude of below 6500 feet, it is possible to find four types of clouds – the cumulus, the stratus, the strato cumulus and the nimbo stratus. Cumulus refers to the shape of the cloud; they would look piled up on top like a cauliflower or a cotton ball, and have a flat base. Stratus can be thin or thick and they are light grey because they are made of water droplets. You add the prefix nimbo to it and we get a cloud that holds a promise of rain or some other form of precipitation. The strato cumulus would be , as the name suggests, light grey, and piled up or puffed up at the top.
Above these low altitude clouds, we can see two types of clouds at a height of 6500 to 20,000 feet. These are the alto cumulus and alto stratus clouds. Alto means medium high and the rest of the meaning is clear from the name. The alto cumulus clouds though puffy, are often seen like long bands.
The high altitude cirro clouds come next. Seen at an altitude of more than 18,000 feet, these include the cirro cumulus, cirrus and cirro stratus. These high altitude clouds are mostly made of ice crystals, not water. The cirrus clouds are thin and wispy, and the cirro cumulus has a wavy look too.
The cumulo nimbus clouds can be seen anywhere between near the ground to a very high altitude. These are the thunder clouds, also known as thunderheads. These are the ones responsible for thunder showers. When they are closer to the ground, the lightning can be dangerous, and we hear the thunder almost at the same time as we see the lightning. When they are very high, the lightning would not be dangerous at all.
Besides these commonly known types of clouds, there are some others like the mammatus clouds that are seen after a tornado, the orographic clouds and pileus clouds that are seen above the mountains. The mammatus clouds have a sagging look and are grayish. The types of clouds seen above the mountains are white and look very smooth. Besides these, there is the long tail like cloud formed by the condensation of the exhaust from airplanes flying at a very high altitude. This is called contrail.