Clouds are generally classified based on characteristics, such as,
altitude, appearance, or origin. Altitude distinctions apply to those
clouds that fit in various layers of the atmosphere as follows:
- high clouds - have bases above 18,000
feet
- middle clouds - have bases between
7,000 and 18,000 feet
- low clouds - have bases below 7,000
feet
- fog - cloud in contact with the ground
- multi-level clouds... vertically thick
spanning multiple layers
- orographic clouds - distinct clouds
that form via interaction between wind and mountainous terrain
features
In appearance, clouds may be thick or thin,
have well defined edges or be very diffuse, appear hairlike, cellular,
towering, or in sheets, and be associated with fair weather or
precipitation. Most clouds owe their existence to upward vertical motion
of air, hence they are often associated with weather producing phenomena,
such as fronts, troughs, and low pressure systems. However, topography can
also help move air upwards and produce clouds. |