Clouds & Precipitation

Saturation vs. Air Temperature

The actual amount ofWater air can hold changesWith air temperature

Air at 104 F can hold 3 timesAs much water as 68 F air !(47 grams vs only 15 grams)

Air at 68 F can hold 4 timesAs much water as air at 0 F(15 grams vs only 4 grams)

32 F

68 F

104 F

4 grams

15 grams

47 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• Orographic Uplift

http://images.google.com/imgres?imgurl=http://earthweb.ess.washington.edu/roe/Web_page_314/index_files/lenticularlogo.jpg&imgrefurl=http://earthweb.ess.washington.edu/roe/Web_page_314/Week4/index.html&h=450&w=668&sz=22&hl=en&start=10&tbnid=dn1oMmwgMlZDOM:&tbnh=93&tbnw=138&prev=/images?q=lenticular+clouds&svnum=10&hl=en&lr=&sa=G

Orographic Uplift

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

Lenticular

Lenticular

Iridescent Cloud

http://apod.nasa.gov/apod/ap071125.html

Cumulonimbus

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://visualfunhouse.com/wp-content/uploads/2007/12/mammatus_cloud_illusion-03.jpeg

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http://californiabirdwatching.files.wordpress.com/2007/07/fluffy-clouds-resize1.jpg

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http://www.tagbanger.com/wp-content/uploads/2007/09/lenticular-clouds.jpg

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http://anomalyblog.files.wordpress.com/2007/01/cloud2.jpg

Nacreous Noctilucent

???

apod.nasa.gov/apod/ap060329.html

Precipitation• The type of precipitation that reaches the

ground depends on processes in the cloud and temperatures between the cloud and the ground.

Precipitation Types / Properties

Global Precipitation

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