Clouds room condensed droplets or ice cream crystals indigenous atmospheric water vapor. Clouds kind by the rising and also cooling of air brought about by convection, topography, convergence, and also frontal lifting. Convection occurs when the Sun"s radiation heats the floor surface, and also warm air rises, cooling together it goes. Air additionally is cooled if an air mass is compelled to move upward as a an outcome of greater topography (e.g., a mountain range) in a process known as orographic lifting. Interestingly, as soon as the wait mass descends top top the other side the the mountain, the warms and the clouds may disappear as the droplets transfer earlier to vapor. *

The counterclockwise activity of a low-pressure facility draws air inward, and the convergence forces the air upward. Air likewise is lifted and also cooled along either a cold front or a warm front. A cold former is the leading edge that an air mass the is colder than the air it is replacing. The front creates a wedge that pushes under the warmer wait ahead, lifting it. A heat front is the top edge the an air mass warmer 보다 the air it is replacing. Together the waiting mass pushes forward, the heat air slides up end the wedge the cold air ahead of it, as shown in the complying with figure.

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category of Clouds

Clouds are classified based upon their shape and also the elevation of the cloud"s base above the ground. The most typical shapes are cirriform, showing up feathery or fibrous; stratoform, appearing layered; and cumuloform, showing up as if piled up. Two extr words provided to describe clouds room "nimbus," meaning rain, and also "alto," definition middle. An easy cloud types are based upon height above the floor surface and on the cloud"s upright development, together summarized below.

High clouds (cloud base over 7 kilometers or 23,000 feet). Typically consisting of ice crystals, these incorporate cirrus, cirrostratus, and also cirrocumulus. middle clouds (2 to 7 kilometers or 6,500 to 23,000 feet). Consisting of liquid droplets, these include altocumulus and altostratus. short clouds (below 2 kilometers or 6,500 feet). Consists of liquid droplets, these encompass stratus, stratocumulus, and also nimbostratus. Clouds that vertical breakthrough (cloud base generally is in the low cloud range, but the tops may reach great heights). These include cumulus clouds and also the towering cumulonimbus. *

Fog to represent a special case of cloud-like formation. Although no truly a cloud, fog is basically stratoform clouds top top the ground.

Cumulus Clouds.

Cumulus clouds are amongst the most interesting in terms of their shapes, i m sorry stir peoples" creativity and permit them to watch a variety of "objects" or "scenes" in the sky. All cumulus clouds have two attributes in common. They have tendency to be bulbous or popcorn-like ~ above top, and have fairly flat bottoms. Why execute they every share these features?

Cumulus clouds are classified as clouds of upright extent. They type as air moves vertically, cooling until the water vapor in the air condenses. This vertical movement is the crucial to understanding the flat-bottomed personality of these clouds. In a offered area, for a offered air mass, it is common to uncover that the cooling rate of ascending air is reasonably constant. In other words, increasing air will certainly cool come a certain temperature in ~ the same height over the ground transparent the area. Air relocating vertically in that area will certainly reach the condensation temperature in ~ the same height over the ground and cloud formation will begin at that height. Consequently, the base of the cloud will be in ~ the same elevation throughout and the cloud"s basic will show up flat.

together the air proceeds to rise and water vapor proceeds to condense, the cloud will expand vertically. The obelisk of rising air actually consists of a number of currents v slightly different directions and also may relocate as pulses. This currents relocate upward together they condense and give rise to the supposedly independent bulbous lobes that the cloud.

Precipitation species

Precipitation aspects begin to form in the part of the cloud wherein ice crystals and also cloud droplets coexist. Many precipitation beginning out together snow, other than for rain that comes the end of very low clouds. Precipitation will remain snow uneven it drops through a class of warmer air, in which case it will certainly melt and remain rain unless it falls through a cooler layer the air, whereby it may freeze and become sleet or ice pellets (as displayed in the following figure). When the air in ~ the ground level is listed below freezing, the raindrops deserve to freeze as soon as they fight the soil or other cold surfaces: that is then called freezing rain.


Hail is formed when a particle, prefer dust, attractive a drop of humidity to itself. The bit gets blown upward by strong updrafts in the cloud, and also freezes together it goes through a chillier layer the air. It is heavier and also begins to fall, attracts more moisture and also then gets compelled upward again and also again adding much more frozen layers.

The differing intensities of rainfall have specific names. Fluid precipitation that is of a longer duration and larger drop dimension is dubbed rain; once it drops in much shorter spurts it is dubbed a shower. Rain commonly falls from lowlevel stratoform clouds with greater vertical extent. Once the fall are really small, rain is referred to as drizzle. A raindrop is about 1,000 times bigger than drizzle.


Thunderstorms go through stages of breakthrough from the start cumulus stage, once the cloud starts to prosper vertically; to the mature stage, once heights may reach from 12 to 18 kilometers (8 come 11 miles); to the dissipating phase (see number below).

In the cumulus stage, there is an updraft of warm air transparent the cloud, as displayed in part (a) of the figure. As the heat updraft increases, the


This schematic illustrates the three general stages of thunderstorm development. An elevation of 40,000 feet is equivalent to 12 kilometers or 8 miles.
cloud build well above the freezing level (the point at i beg your pardon the temperature of the increasing air has actually cooled come water"s freeze point). The precipitation particles prosper larger and also become heavier. The increasing air soon cannot hold them up, and also they begin to fall. The corpuscle drag several of the air together with them, producing a downdraft, as shown in part (b) of the figure.

together the updraft pulls more dry air right into the cloud, some of the raindrops evaporate, and the wait cools, making the colder and also heavier than the surrounding air. This commonly strengthens the downdraft. The fallout’s precipitation causes more downdrafts to form throughout the cloud, beginning the dissipating stage, as presented in part (c) of the figure. During the dissipating stage, precipitation wake up from the entire cloud base.

some thunderstorms can build into present of severe thunderstorms, developing high winds, hail, constant lightning, heavy rain, flash floods, and even tornadoes.

SEE additionally Climate Moderator, Water as a ; Hydrologic cycle ; Precipitation, global Distribution the ; Weather and also the ocean .

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Internet resource

"Clouds and also Precipitation." WW2010 Weather people Project, department of Atmospheric Sciences, university of Illinois in ~ Urbana-Champaign. .

* see "Climate Moderator, Water as a" because that a chart of orographic lifting and the rain shadow effect.

* check out "Precipitation, an international Distribution of" for a photograph of a cloud of vertical development.