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CARTOON
HUMIDITY
 The amount of water vapor in the air.
 Relative Humidity: How much water a parcel of air is capable of holding.
 Changes with temperature

Warm Air can hold more water

Cold Air is capable of holding less water
 When air is full of water we call it saturated.
 What is a Parcel:
 Think balloon containing air
DEW POINT
 Temperature air needs to be cooled to until it can hold no more water
 At this point water will condense
 On the right stuff this
condensation of water forms clouds
 Water Droplets Require Condensations Nuclei
 Usually dust, dirt, aerosol particles
 When lifted, cold air reaches
its dew point faster than warm air.
Dew ≠ Rain
Cloud Condensation ≠ Rain
CARTOON
HOW DO CLOUDS FORM?
1st Step: We Need Condensation
Nuclei
 What’s that?
 Something for water droplets to
condense on.
 Usually dust, dirt, aerosol particles
2nd Step: Air Needs to Be Lifted
 Moist Air Rises and Expands but
needs to be forced upward so it
can cool down enough to hit its
dew point.
 Most Common:
 1). Lifted Over A Mountain…
 Orographic Lifting
 2). Frontal Wedging
 Meeting a very different air mass
SOMEHOW….WE NEED TO GET AIR TO
RISE…
 Orographic Lifting:

Mountain is more dense,
So the air rises over.
 Frontal Wedging

Meeting a very
different air mass;
body of air.

We know cold air is very
dense, so warm air is forced
up and over.
Dry adiabatic cooling rate
*10C/1000 m
Air only stops cooling at this rate when it hits its dew point
and begins to condense.
TYPES OF CLOUDS
Height Descriptions = Prefixes
 1). Cirro:Very High Clouds
Shape = 2nd half
 Cirrus: Thin Wispy

 2). Alto: Middle Clouds
like hair
 Cumulus: Big Puffy/
 Lumpy Clouds
 Cotton Balls
 3). Strato: Low Clouds
 Stratus: Continuous
Cloud
Nimbus = Storm Cloud
CLOUD VIDEOS
 http://www.youtube.com/watch?v=velxZEWhrDo
 http://www.youtube.com/watch?v=mZnmQ0mnTnU&feature=fvwrel
CLOUD
MATCHING GAME
http://eo.ucar.edu/webweather/cloud
match.html
IDENTIFY THAT CLOUD
Cirrus
IDENTIFY THAT CLOUD
Cirrocumulus
IDENTIFY THAT CLOUD
Cirrostratus
IDENTIFY THAT CLOUD
Altostratus
IDENTIFY THAT CLOUD
Altocumulus
IDENTIFY THAT CLOUD
Stratocumulus
IDENTIFY THAT CLOUD
Cumulonimbus
IDENTIFY THAT CLOUD
Stratonimbus
OPTIONS
 Electromagnetic Spectrum Web Quest:

http://missionscience.nasa.gov/ems/01_intro.html
 Layers of the Atmosphere/Methods of Heat Transfer
 http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/layers.html
QUESTION OF THE DAY
 What is convection?
 How is convection related to weather?
FOG
 When the dew point of water vapor is reached close to the surface;
clouds forming on Earth’s surface.
 Advection Fog: Happens during the morning hours
 Horizontal movement of warm moist air from over water to land where
temperatures are cooler.
 Radiation Fog: happens on cool/clear nights
 Heat escapes from Earth vertically; lost to space.
 Earth cools down so that air can reach its dew point at the surface.
TYPES OF STABILITY
Stable Atmosphere
Unstable Atmosphere
 Air is sinking; high pressure
 Air is rising; low pressure
 Clouds are thin or not present
 Clouds tall
 Intense Precipitation possible
 Severe storms possible
CARTOON