Low Clouds
A term used to signify clouds with bases below 6,000 feet and are of a stratiform or a cumuliform variety. Stratiform clouds include stratus and stratocumulus. Cumuliform clouds include cumulus and cumulonimbus. This altitude applies to the temperate zone. In the polar regions, these clouds may be found at lower altitudes. In the tropics, the defining altitudes for cloud types are generally higher.
Stratiform
Clouds composed of water droplets that exhibit no or have very little vertical development. The density of the droplets often blocks sunlight, casting shadows on the earth’s surface. Bases of these clouds are generally no more than 6,000 feet above the ground. They are classified as low clouds, and include all varieties of stratus and stratocumulus. The opposite in type are the vertical development of cumuliform clouds.
Cumuliform
Clouds composed of water droplets that exhibit vertical development. The density of the droplets often blocks sunlight, casting shadows on the earth’s surface. With increasing vertical height, they are often associated with convection. Bases of these clouds are generally no more than 3,000 feet above the ground, but they can develop past the troposphere in both temperate and tropical latitudes. They are classified as low clouds and include all varieties of cumulus and cumulonimbus. The opposite in type are the horizontal development of stratiform clouds.
Stratus
One of the three basic cloud forms (the others are cirrus and cumulus. It is also one of the two low cloud types. It is a sheetlike cloud that does not exhibit individual elements, and is, perhaps, the most common of all low clouds. Thick and gray, it is seen in low, uniform layers and rarely extends higher than 5,000 feet above the earth’s surface. A veil of stratus may give the sky a hazy appearance. Fog may form from a stratus cloud that touches the ground. Although it can produce drizzle or snow, it rarely produces heavy precipitation. Clouds producing heavy precipitation may exist above a layer of stratus.
Stratocumulus
A low cloud composed of layers or patches of cloud elements. It can form from cumulus clouds becoming more stratiformed and often appears as regularly arranged elements that may be tessellated, rounded, or roll-shaped with relatively flat tops and bases. It is light or dark gray in color, depending on the size of the water droplets and the amount of sunlight that is passing through them.
Cumulus
One of the three basic cloud forms (the others are cirrus and stratus). It is also one of the two low cloud types. A cloud that develops in a vertical direction from the base (bottom) up. They have flat bases and dome- or cauliflower-shaped upper surfaces. The base of the cloud is often no more than 3,000 feet above the ground, but the top often varies in height. Small, separate cumulus are associated with fair weather (cumulus humilis). With additional heating from the earth’s surface, they can grow vertically throughout the day. The top of such a cloud can easily reach 20,000 or more into the troposphere. Under certain atmospheric conditions, these clouds can develop into larger clouds, known as towering cumulus (cumulus congestus), and may produce a rain shower. Further development may create a cumulonimbus.
Cumulonimbus
A vertically developed cumulus cloud, often capped by an anvil-shaped cirriform cloud. Also called a thunderstorm cloud, it is frequently accompanied by heavy showers, lightning, thunder, and sometimes hail, tornadoes or strong, gusty winds.
Temperate Climate
Climates with distinct winter and summer seasons, typical of regions found between the Tropics of Cancer and Capricorn and the Arctic and Antarctic Circles. Considered the climate of the middle latitudes.
Poles / Polar
The poles are the geographic point at 90 degrees latitude North and South on the earth’s surface. They are equal distance from the equator. The polar region is considered to be that area between 60° and 90° latitude, both North and South.
Tropics / Tropical
The region of the earth located between the Tropic of Cancer, at 23.5 degrees North latitude, and the Tropic of Capricorn, at 23.5 degrees South latitude. It encompasses the equatorial region, an area of high temperatures and considerable precipitation during part of the year.