They may appear feathery, lumpy, pouch-like … may bring fair weather or a forerunner of typhoons and tornadoes but we can’t deny that these clouds are simply amazing.
Cirrus clouds are the most common type of high-level clouds. They usually denote fair weather. Cirrus clouds appear white and feathery which form above 6000 m (20,000 ft). Made up primarily of ice crystal, they may appear in various shapes and sizes. Also, cirrus clouds have subtypes. The two main subtypes are cirrostratus, which resemble as thin blanketing cloud covering the sky and cirrocumulus that appears like a plate of bubble wrap. Cirrus clouds normally move across the sky from west to east.
Contrails or vapor trails are clouds of ice particles formed by the exhaust of aircraft engines. It is the product of hot exhaust gases from the jet’s engine combining with the cool environmental air. Depending on the whether condition, contrails may last for a few hours or for just a few seconds or minute (if the air is somewhat moist).
Nimbostratus clouds belong to the low-level clouds forming their base between the surface and up to 2000 m. They are dark gray, formless cloud layer with a tattered base typically covering the whole sky in a thick layer. Though appearing worldwide, nimbostratus are common cloud type in temperate regions. These clouds occur along warm fronts and normally bring rains.
Altostratus are middle height clouds (altitude from 2,400–6,100 m) characterized by a gray or bluish layer of evenly and opaquely appearance. These clouds are formed when a front of warm air is lifted into higher altitudes then condensed. Altostratus are mainly composed of water droplets. They usually covers the sky but having some thin layers, the sun or moon shine through only a little. If these clouds thicken, then occasionally rain or snow follows.
Orographic photo link
Orographic clouds are form when an air mass is lifted from a low altitude to a higher altitude caused by the earth’s topography such as mountain ranges. Air oscillates as it passes over a mountain and as it moves downstream. As the air cools, water vapor condenses and form as clouds. Normally, an orographic lifting (upslope flow) produces cooler and moist weather.
Stratocumulus cloud fall under the Low Cloud class (surface-2000m).These clouds are characterized by its broad dark gray horizontal layers, uniform base, and rounded summits. These layers of lumpy cloud are formed by weak, shallow convection currents. It is not a bad weather cloud, though it usually appears before or after a worse weather condition.
Cumulonimbus, known as thunderstorm cloud, is a tall, dense and dark cloud that forms vertically through all cloud levels. The largest of clouds, it can reach up to 10km high with a base several miles across. Cumulonimbus clouds are form when a front of cool air meets a body of hot, moist air. They are normally associated with heavy rain showers, lightning, snow showers, thunderstorms and tornadoes.
Mammatus, also known as mammatocumulus are rare pouch-like a bluish gray cloud that only appear where cumulonimbus clouds are present. They are characterized as smooth, tattered or lobes having lumps and may be opaque in appearance. Mammatus can last from minutes to hours. Contrary to common misconceptions, mammatus clouds are not forerunner to tornadoes, but rather a product after a thunderstorm has passed
Billow clouds, also known as undulates, are parallel rolls of cloud, formed from shear instability (Kelvin–Helmholtz), associated with air flows having different velocities brushing one another Billow clouds appear when there is enough moisture present in the upward motion of the waves to make the wave formation evident by condensation of cloud droplets. Billow clouds may appear at many different levels in the atmosphere.
A pileus, also called cap cloud, is a thin, horizontal cloud made of ice crystals that can appear on the top of a cumulus or cumulonimbus cloud. They are formed as a result of strong uplift of a moist layer of air causing condensation in this layer. Pileus clouds show strong winds and an indicator that an impending storm is approaching.