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Clouds & Precipitation
Clouds & Precipitation
Let’s Review• Evaporation - The changing of a liquid into a
gas, often under the influence of heat.
• Condensation - The conversion of a vapor or gas to a liquid.
• Sublimation – to be transformed directly from
the solid to the gaseous state or from the
gaseous to the solid state without becoming
a liquid.
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)
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
Dew Point -The temperatureat which watervapor in the airbecomessaturated andwater dropletsbegin to form
• Dew Point - The temperature at which water
vapor in the air becomes saturated and
water droplets begin to form
• Relative humidity. – The amount of water vapor in the air at any given time is usually less than that required to saturate the air. The relative humidity is the percent of saturation humidity, generally calculated in relation to saturated vapor density.
• actual vapor density
• Relative Humidity= saturation vapor density X 100
CLOUDS
• A cloud is billion of 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 tothe 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
Orographic Uplift
CONVECTIONAL
FRONTAL CLOUD
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
