High clouds are anywhere from 5,000m-13,000m high. Some examples of these kinds of clouds are cirrus and cirrocumulus. Contrails are also included in this altitude.
Middle clouds are located anywhere from 2,000m-7,000m high. Examples of these clouds are altocumulus and altostratus.
Low clouds are located from the surface up to 2,000m. Examples of these clouds are cumulus and cumulonimbus.
Cloud height depends on factors such as region.
There are also clouds located in the stratosphere and they are called polar stratospheric clouds. The mesoshpere aslo has clouds called polar mesoshperic clouds.
The lowest level of clouds are "stratus" clouds that often fill the entire sky but rarely drop precipitation and are often similar to fog. Nimbostratus clouds are slightly higher and do often drop light precipitation.
The next level includes Altocumulus which are grey and puffy and often signify thunderstorms on the way and Altostratus clouds that fill more of the sky and are often thin enough to allow the sun to shine through dimly and produce steady precipitation.
The higher clouds are usually Cirrus clouds, thin and whispy, generally you see them when the weather is really nice. They are often at or above 20,000ft making them truly "high" clouds.
Scientists often group clouds in groups of low clouds, middle clouds and high clouds, according to their height above the ground at which they form. A stratus cloud looks like a smooth, even sheet. A stratocumulus has light and dark areas on the bottom, indicating presence of piles of clouds in the layer.
The low clouds are are usually seen near the earth surface, less than 1800 meters above the ground. These are further classified as stratus and stratocumulus clouds according to their shape and colour.
Middle clouds lie from 1800 to 6000metersabove the earths surface. These are further classified as altostratus, altocumulus, and nimbostratus clouds. An altostratus cloud forms a smooth white or grey sheet across the sky that appears in many shapes. It may be like unconnected piles or a layer of clouds piled together. A nimbostratus cloud is a smooth layer of grey.
High clouds sometimes appear at height of more than 10,000 meters above the earth's surface. These clouds are formed entirely of ice crystals. These clouds are further classified as cirrus, cirrostratus, and cirrocumulus clouds. Cirrus clouds are the delicate wispy clouds that form high in the sky, sometimes higher than 10,000 metres. A cirrostratus cloud looks like a thin sheet. Cirrocumulus clouds look like many small tufts of cotton in the sky.
Some clouds appear at more than on height. For example, cumulus and cumulonimbus clouds may rise to great heights while their bases are near the ground. A cumulonimbus cloud may reach heights as great as 18,000 metres from its base so that its top consists of only ice crystals.