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CP Sci 9- 1st Sem.

Gen Chem - 1st Sem.

Clouds

Objectives:

    1.    Describe the three basic forms of clouds.

    2.    Explain how the shape of a cloud how air is moving through it.

Key Terms:

    stratus    cumulus    cirrus    condensation level    dry-adiabatic lapse rate    moist-adiabatic rate

Notes: (18.2)

Clouds are present all around us practically every day of the year.  The formation and type is dependant on the temperature, pressure, amount and level of moisture, and the particulate matter present in the atmosphere.  The formation of clouds requires condensation and cooling and a set of specific conditions.

bulletcondensation nuclei - piece of dust, salt, soot
bulletair must cool at or below the dew point
bullet    without condensation nuclei air may become super saturated - containing water above its carrying capacity

Fog and Frost

Fog and frost are formed as air comes into contact with a colder surface that is at or below the dew point of the air.   The temperature of the air determines whether fog and frost forms is the air temperature.  If the temp is above 0oC fog forms and visa-versa.  The type of fog formed is determined by the conditions surrounding it.

bulletRadiation fog - Warm ground radiates heat and eventually becomes cooler than the air above it.  Fog forms as a result of convection currents at the Earth's surface.

Radiation Fog Formation

(members.shaw.ca/keithheidorn/ wxdrphotos/radiationfog.gif)

bulletAdvection fog - Warm moist air blows over a cold surface.

Advection Fog Formation

(members.shaw.ca/keithheidorn/ wxdrphotos/advectionfog.gif)

Types of Clouds

Clouds are formed as warm moist air rises, cools around droplet nuclei and becomes saturated.  As the temperature passes the dew point water droplets begin to form.  When millions get together they form clouds.  Clouds are classified according to their height and shape.

Classification: Shape & Height

    Shape

bullet

Stratus form horizontal layers, smooth, low altitudes

Historic NWS Image - wea02047

(www.photolib.noaa.gov/historic/ nws/images/big/wea02047.jpg)
bullet

Cirrus - feathery - high altitudes  

 

 

 

 

 

 

 

(www.mmem.spschools.org/grade5science/ weather/cirrus.jpeg)
bullet

Cumulus vertical air movement puffy white , cauliflower clouds

bullet

Form when air currents rise

bullet

Many have flat bases

(strike.colorado.edu/.../ cumulous_cloud.jpg)

 Height

bullet

Cirrus Above 7000 meters

bullet

    Cirrostratus - high fibrous clouds - feathery

bullet

    Cirrocumulus - Containing ice crystals

 

 

 

 

 

 

 

 

(www.mmem.spschools.org/.../ weather/cirrus.jpeg)

 

(web.ukonline.co.uk/ mark.shufflebottom/images/...)

 
bullet

Alto - 2000 - 7000 meters

bullet

    Altostratus

bullet

    Altocumulus

(www.sky-fire.tv/.../ cloudtypes/altostratus.jpg)

(asd-www.larc.nasa.gov/.../ altocu.thumb.jpg)

(vortex.plymouth.edu/cu03.jpg)
bullet

Strato - below 2000 meters

bullet

    Stratus - fog

bullet

    stratocumulus

 

Clouds associated with precipitation

Meteorologists use the adiabatic (absorption of heat without a change of temperature) cooling rates of dry and moist air and the dropping dew point to predict rain and precipitation levels.  

bullet

Nimbus associated with precipitation

bullet

    Nimbostratus - rain clouds

bullet

    Cumulonimbus

bullet

    When the water droplets get larger than 0.2mm they form precipitation (rain).  Type depends of temp.

bullet

All the clouds mix to form tall cumulonimbus clouds that can bring severe thunderstorms - called storm heads, thunder heads, anvil heads

bullet

When the water droplets get larger than 0.2mm they form precipitation.  Type depends of temp.

(www.uwsp.edu/.../atmosphere/clouds/ cumulonimbus_small.jpg)

 

 

 

 

 

 

Last modified: September 05, 2004