Cumulus cloud

Cumulus Cloud
{{{image name}}}
Abbreviation Cu
Genus Cumulus (heap)
Altitude Base usually below 2,000 m (below 6,500 ft)
but may be higher (mid-level altitude) during conditions of very low relative humidity. (tops vary)
Classification moderate vertical (family D1) or towering vertical (family D2).
Appearance puffy
Precipitation cloud? Depends. Cumulus humilis and mediocris, most likely no, but congestus and castellanus sometimes yes. Cumulonimbus, yes, but may be virga.
v · d · e

Cumulus clouds are a type of cloud with noticeable vertical development and clearly defined edges. Cumulus means "heap" or "pile" in Latin. They are often described as "puffy" or "cotton-like" in appearance. Cumulus clouds may appear alone, in lines, or in clusters. Cumulus clouds are often precursors of other types of clouds, such as cumulonimbus, when influenced by weather factors such as instability, moisture, and temperature gradient. Cumulus clouds are part of the larger category of cumuliform clouds, which include cumulus, cumulus congestus, and cumulonimbus clouds, among others.[1] The most intense cumulus and cumulonimbus clouds may be associated with severe weather phenomena such as hail, waterspouts and tornadoes.



Cumulus mediocris from above
Cumulus clouds in the foreground and background with stratocumulus in between

Cumulus clouds typically form when warm air rises and reaches a level of cool air, where the moisture in the air condenses. This usually happens through convection, where a parcel of air is warmer than the surrounding air.[2] As it rises, the air cools at the dry adiabatic lapse rate (approximately 3°C per 1000 ft or 1°C per 100 m), while the dewpoint of the air falls by 0.5°C per 1000 ft.[3] When the temperature of the air reaches the dewpoint, some water condenses out of the air to form the cloud. The size of the cloud depends on the temperature profile of the atmosphere and the presence of any inversion. If the top of the cumulus cloud reaches above the altitude where the temperature is at or below the freezing level, then precipitation from the cloud is possible.[4] The temperature of the air at ground level will determine if this falls as rain or snow.

Simplified development of a cumulus cloud, given conditions are suitable.

In windy conditions, the clouds can form lines (cloud streets) parallel with the wind.[5] In mountainous areas, they may also form lines at an angle to the wind, due to the presence of lee waves above the clouds.[6] They form around 0 feet in the air.

Over the sea cumulus clouds may be found in regularly spaced lines or patterns.[7] The best examples of these lines are found in the trade winds, where they may extend for many miles[vague]. Such lines create a pattern in the vertical movement of air, causing it to roll horizontally. Between the lines of cloud are stronger, more gusty, and slightly veering winds, but beneath the lines of cloud, somewhat lighter and more backing winds prevail.

The height at which the cloud starts to form (cloud base) depends on the amount of moisture in the air parcel that forms the cloud. Humid air will generally result in a lower cloud base.[8] In temperate areas, the base of the cumulus clouds is usually up to 8,000 ft (2,400 m) in altitude. In arid and mountainous areas, the cloudbase can be in excess of 20,000 ft (6,000 m).

Glider pilots often pay close attention to cumulus clouds, as they can be indicators of rising air drafts or thermals underneath.[5]


Cumulus humilis clouds, appearing as small- or medium-sized puffy shapes in the sky, often occur in times of fair weather.[9] However, cumulus clouds can grow into cumulonimbus clouds which may produce heavy rain, lightning, severe and strong winds, hail, and even tornadoes.[10][11] Cumulus congestus clouds, which appear as towers, will often grow into cumulonimbus storm clouds.

Cumulonimbus Cloud Formation Over Central Florida


  1. ^ Cumuliform clouds: some examples. Accessed 2009-11-08.
  2. ^ "BBC - Cumulus Clouds". Retrieved 2008-08-15. 
  3. ^ Brunt, D (1939). Physical and Dynamical Meteorology. London: Cambridge University Press. 
  4. ^ Mossop, S C; Hallett J (November 1974). Ice Crystal Concentration in Cumulus Clouds: Influence of the Drop Spectrum: Science. AAAS. 
  5. ^ a b "Pilot Outlook - Cloud Streets". Retrieved 2008-08-13. 
  6. ^ "Wave Soaring Over the British Isles". Retrieved 2008-10-02. [dead link]
  7. ^ Russell, Sharman. "The Language of Clouds". Natural Resources Defense Council. Retrieved 2008-10-14. 
  8. ^ "ARIC - Cumulus Clouds". Retrieved 2008-08-16. 
  9. ^ "Michigan Tech - Cumulus Clouds". Archived from the original on 2008-06-18. Retrieved 2008-08-13. 
  10. ^ Palmer, Chad (2005-10-16). "USA Today - Cumulus Clouds". Retrieved 2008-08-13. 
  11. ^ Thompson, Philip; Robert O'Brien (1965). Weather. New York: Time Inc.. pp. 86–87. 

External links

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • cumulus cloud — noun a globular cloud • Syn: ↑cumulus • Hypernyms: ↑cloud • Hyponyms: ↑altocumulus, ↑altocumulus cloud, ↑thunderhead …   Useful english dictionary

  • cumulus cloud —    Ōpua, kaha ea …   English-Hawaiian dictionary

  • Towering cumulus cloud — Towering cumulus clouds, photographed from an airplane Towering cumulus clouds can be based in the low or middle height ranges and achieve considerable vertical development (family D2) in areas of deep, moist convection. They are an intermediate… …   Wikipedia

  • Cumulus — may refer to:*Cumulus cloud, a type of cloud *Cumulus Media, a radio broadcasting company *Cumulus (software), digital asset management software developed by Canto Software * Cumulus (synthesizer), GPL software synthesizer using grain synthesis …   Wikipedia

  • Cloud — For other uses, see Cloud (disambiguation). Cumulus cloudscape over Swifts Creek, Australia A cloud …   Wikipedia

  • Cloud suck — Towering cumulus clouds are often associated with cloud suck Cloud suck is a phenomenon commonly known in paragliding and hang gliding where pilots experience significant lift due to a thermal under the base of cumulus clouds, especially towering …   Wikipedia

  • cumulus — Synonyms and related words: Cloudcuckooland, alto cumulus, alto stratus, anvil cloud, banner cloud, billowy cloud, cap cloud, cirro cumulus, cirro fillum, cirro nebula, cirro stratus, cirro velum, cirrus, cirrus cloud, cirrus haze, cirrus stripe …   Moby Thesaurus

  • Cumulus castellanus cloud — Infobox Cloud name = Cumulus castellanus image location = CuCa.jpg altitude = appearance = Flat on the bottom, though has multiple towers on top precipitation = Usually no, but can grow into cumulonimbus clouds abbreviation = Cumulus castellanus… …   Wikipedia

  • cloud — I (New American Roget s College Thesaurus) n. haze (see cloudiness, obscurity); flight (see assemblage). II (Roget s IV) n. 1. [Fog at a distance from the earth] Syn. haze, mist, rack, fogginess, haziness, film, puff, billow, frost, nebula,… …   English dictionary for students

  • cumulus — Clouds with marked vertical development. Cumulus clouds are billowing, white, flat based, individual clouds with a pronounced thickness, which extends upward as a cauliflower or as a dome. These are fair weather type clouds initially, but they… …   Aviation dictionary

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.