Observing Climate - Upper Air 3-1 Water (Con t) Clouds Types - Classification Base height Coverage Science Concepts Definition The Earth System (Kump, Kastin & Crane) Chap. 3 (pp. 48-49)
3-2 What do we want to know about clouds and cloud cover? Rain or no rain Liquid or ice Height Percentage of sky covered by cloud Formation process
3-3 Definition Clouds are water vapor that has changed to a solid (deposition) or liquid (condensation) in the atmosphere Classification Named by formation mechanism (causes shape), by level, by rain or no rain, etc. A stanza of The Cloud I am the daughter of Earth and Water, And the nursling of the sky; I pass through the pores of the ocean and shores; I change, but I cannot die. Percy Bysshe Shelley Several root words from Greek are key to a cloud classification scheme - cirro > Hair like, fibrous aspect and/or milky sheen - cumulo > Puffy, detached modules - strato > Layer like - nimbo > Rain
3-4 Classification (Con t) Root words that refer to cloud height - Cirriform > Cloud types with the highest altitude bases; composed of ice crystals, very cold, bases 6 km and higher - Altoform > Middle level clouds with intermediate altitude bases; composed of ice, super-cooled water drops or drops above freezing, bases between 2 and 6 km - Stratoform > Cloud types with lowest altitude bases; usually warm (above freezing) clouds composed of water drops above freezing (but may be ice crystals in winter), bases from the surface to 2 km Clouds with Vertical Development - Composed of all possibilities above depending on cloud temperature
Classification (Con t) 3-5 http://shop.usps.com/cgi-bin/vsbv/postal_store_non_ssl/html/clouds.html Examples of Cloud Names - Who and when defined - High Clouds > Cirrus (Ci) - Howard (1803) > Cirrostratus (Cs) - Howard (1803) > Cirrocumulus (Cc) - Howard (1803)
Classification (Con t) 3-6 http://shop.usps.com/cgi-bin/vsbv/postal_store_non_ssl/html/clouds.html Examples of Cloud Names Middle Clouds > Altostratus (As) - Renou (1870) Middle clouds composed of gray or blue layers of uniform appearance. Snow or rain may fall from these clouds > Altocumulus (Ac) - Renou (1870)
3-7 Classification (Con t) http://shop.usps.com/cgi-bin/vsbv/postal_store_non_ssl/html/clouds.html Examples of Cloud Names - Low Clouds > Stratus (St) - Howard (1803) > Stratocumulus (Sc) - Kaemtz (1841) > Nimbostratus (Ns) - International Commission for the Study of Clouds (1930) Dark, gray clouds characterized by more or less continuously falling precipitation, usually rain, not accompanied by lightning, thunder, or hail
Classification (Con t) 3-8 http://shop.usps.com/cgi-bin/vsbv/postal_store_non_ssl/html/clouds.html Examples of Cloud Names Clouds with Vertical Development > Cumulus or Fair weather cumulus Individual, detached heaps or towers that are usually dense and well defined > Cumulus Congestus Individual, detached domes or towers; usually dense and well defined > Cumulonimbus (Cb) Weilbach (1880) Exceptionally dense and vertically developed clouds, often with anvil shaped top, frequently accompanied by heavy showers, lightning, thunder and sometimes hail
3-9 Cloud Observations Ceiling - Height of the lowest layer of clouds above the surface that are either Ceilometer broken or overcast - Automatic instrument used to record ceiling, i.e., the altitude of the lowest cloud layer - Consists essentially of a projector, detector, and recorder - Optical ceilometer uses triangulation to determine height of a spot of light projected onto the base of cloud http://www.weather.gov.hk/aviat/stn_e/ceilometer_e.htm - Laser ceilometer determines height by measuring the time required for a pulse of light to be scattered back from the cloud base Laser Ceilometer
3-10 Cloud Observations (Con t) Cover http://ww2010.atmos.uiuc.edu/(gh)/ guides/maps/sfcobs/wx.rxml