Top 10 clouds facts

Venus. If a planet's atmosphere contains radiatively active gases, they will radiate energy in all directions. Part of this radiation is directed towards the surface, warming it. The greenhouse effect on Venus is particularly large because its dense atmosphere consists mainly of carbon dioxide.

Small droplets or ice crystals. The effect is similar to irisation. Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light. Larger ice crystals do not produce iridescence, but can cause halos, a different phenomenon.

Sulfuric acid. The most important gas which leads to acidification is sulfur dioxide, coming from fossil fuel combustion and industry (and, in lesser amounts, from volcanoes and wildfires). In recent years, emissions of nitrogen oxides which are oxidized to form nitric acid are of increasing importance due to stricter controls on emissions of sulfur containing compounds.

Stratus. The term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color from dark gray to nearly white. Stratus clouds may produce a light drizzle or a small amount of snow. These clouds are essentially above-ground fog formed either through the lifting of morning fog or through cold air moving at low altitudes over a region.

Sunny. These puffy clouds are called "fair weather cumulus". They have little vertical extent and do not give precipitation. When they appear in a clear sky, they are an indicator of pleasant weather for the next several hours.

Iridescence is the phenomenon of certain surfaces that appear to gradually change colour as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, butterfly wings and sea shells, as well as certain minerals. It is often created by structural coloration (microstructures that interfere with light).

Cirrostratus is a high-level, very thin, generally uniform stratiform genus-type of cloud, composed of ice-crystals.

Arcus clouds most frequently form along the leading edge or "gust fronts" of thunderstorm outflow; some of the most dramatic arcus formations mark the gust fronts of derecho-producing convective systems. Roll clouds also may arise in the absence of thunderstorms, forming along the shallow cold air currents of some sea breeze boundaries and cold fronts.

Kármán vortex street. When a cloud layer is present at the relevant altitude, the streets become visible. Such cloud layer vortex streets have been photographed from satellites. Kármán vortex street caused by wind flowing around the Juan Fernández Islands off the Chilean coast. It is named after the engineer and fluid dynamicist Theodore von Kármán.

Morning Glory cloud. The Morning Glory cloud is a roll cloud, or arcus cloud, that can be up to 1,000 km long, 1 to 2 km high and often only 100 to 200 metres above the ground. The southern part of the Gulf of Carpentaria in Northern Australia is the only known location where it can be predicted and observed on a more or less regular basis due to the configuration of land and sea in the area.