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Clouds & Precipitation. Saturation vs. Air Temperature. The actual amount of Water air can hold changes With air temperature Air at 104 F can hold 3 times As much water as 68 F air ! (47 grams vs only 15 grams) Air at 68 F can hold 4 times As much water as air at 0 F
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Saturation vs. Air Temperature The actual amount of Water air can hold changes With air temperature Air at 104 F can hold 3 times As much water as 68 F air ! (47 grams vs only 15 grams) Air at 68 F can hold 4 times As much water as air at 0 F (15 grams vs only 4 grams) 104 F 47 grams 68 F 15 grams 32 F 4 grams
Adiabatic Cooling: Clouds and Lifting Condensation Level (LCL) • LCL / Cloud base = dew point altitude
CLOUDS • A cloud is water vapor condensed around dust particles (condensation nuclei). • At any given time, ~50% of Earth is covered by clouds and about 6% is having precipitation. • The greater the amount of moisture in an air mass, the lower the level of condensation.
CONDENSATION • > 0o C = water droplets (lower levels) • < 0o C = ice crystals (upper levels) • middle levels = mixture of ice and water
Type of cloud depends on… • amount of moisture in the air • degree of uplift • atmospheric stability
NAMING CLOUDS 3 Basic types: • Cirrus – curly or fibrous • Stratus – means “layer”; flat and/or layered • Cumulus – means “heap”; puffy or piled up • The prefixes cirro (high), alto (middle) refer to • the level in the atmosphere. • The prefix nimbo means “rain-bearing”.
Lifting Mechanisms In order to make clouds, the air has to be lifted so that it will condense. • Convection • Frontal Cloud • OrographicUplift
Cumulus http://en.wikipedia.org/wiki/Image:GoldenMedows.jpg
Stratus http://en.wikipedia.org/wiki/Image:FrozenField-Stratus.jpg
Nimbostratus http://en.wikipedia.org/wiki/Image:Nov20-05-Nimbostratus.jpg
Cumulus & Stratocumulus http://www.foundmyself.com/tutorials/text_clouds/clouds_original.jpg
Cirrus http://en.wikipedia.org/wiki/Cirrus_clouds
Cirrus http://en.wikipedia.org/wiki/Cirrus_clouds
Cumulus & Cirrocumulus http://www.bbc.co.uk/theoneshow/gallery/images/user_submitted/clouds/clouds7_450x340.jpg
Cirrostratus with halo http://en.wikipedia.org/wiki/Cirrostratus_cloud
Mammatocumulus http://en.wikipedia.org/wiki/Image:Mammatus_clouds_Milan_July.jpg
Mammatocumulus http://en.wikipedia.org/wiki/Image:Mammatus_Clouds.png
Iridescent Cloud http://apod.nasa.gov/apod/ap071125.html
Cumulonimbus http://en.wikipedia.org/wiki/Image:Anvil_shaped_cumulus_panorama_edit_crop.jpg
Cumulonimbus http://en.wikipedia.org/wiki/Image:CumulonimbusFlorida.jpg
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??? http://californiabirdwatching.files.wordpress.com/2007/07/fluffy-clouds-resize1.jpg
??? http://www.tagbanger.com/wp-content/uploads/2007/09/lenticular-clouds.jpg
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Precipitation • The type of precipitation that reaches the ground depends on processes in the cloud and temperatures between the cloud and the ground.
HAIL • balls or chunks of ice (1cm-5 cm) • grow due to downdrafts/updrafts in cumulonimbus clouds
Snowflakes and Temperature Snow crystal images from an electron microscope