Download Adiabatic Lapse Rates

Adiabatic Lapse Rates
•Adiabatic: "occurring without gain or loss of heat"
•Adiabatic cooling and Heating (Expansion or
compression: adiabatic cooling and heating is a
temperature change without the addition or removal
of heat.
Adiabatic Lapse Rates
• Air rising cools because of expansion of
the air. This cooling causes the air to
reach dew point and form clouds.
• Air sinking compresses and heats up
causing a drying out of the air.
Adiabatic Lapse Rates
• Moist air cools slower than dry air when it
rises. Why? Hint (Think of energy)
• When moist air condenses it releases
energy into the atmosphere which causes
some warming.
Cloud formation
• Condensation nuclei: Liquid or solid particles,
such as those in smoke or dust, that provide a
surface upon which water vapor can condense
into cloud droplets or form ice crystals.
• Water evaporates, rises and cools, reaches dew
point, condenses and form a cloud.
• Fog: Condensed water vapor in cloudlike
masses lying close to the ground and limiting
visibility.
Cloud Formation
• Radiation Fog: Fog produced results from the
air near the ground being cooled to saturation
by contact with the cold ground. The cooling
of the ground results from night time loss of
heat from the Earth to space (terrestrial
radiation).
Cloud Formation
• Advection Fog: Occurs when warm, moist air
moves over a cold surface and the air cools to
below its dew point.
• Frost: A covering of ice produced by water
vapor freezing on exposed surfaces when the
air temperature falls below the frost point.
Cloud Types
• Cirrus: generally refer to atmospheric clouds
that are characterized by thin, wisplike
strands.
Cloud Types
• Stratus Clouds: is a cloud belonging to a
class characterized by horizontal layering
with a uniform base
• Why are some clouds darker than others?
Cloud Types
• Cumulus Clouds: are a type of cloud with
noticeable vertical development and
clearly defined edges. Cumulus means
"heap" or "pile" in Latin
Clouds Types
• Nimbus- means dark rain cloud.
• Alto- means 2000-7000 meters high.
Types of precipitation
• Sleet: raindrops that freeze in the air when
falling from a cloud.
• Freezing Rain: raindrops freeze when they hit
the ground because the ground is below
freezing.
Types of precipitation
• Hail: frozen raindrops that are kept aloft by
strong winds until they are to heavy to stay up.
• Snow: ice crystals in a cloud collide and clump
together.
Precipitation
• Acid Rain: rain containing acids that form in the
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atmosphere when industrial gas emissions (especially
sulfur dioxide and nitrogen oxides) combine with
water
Rain: precipitation of liquid water drops with
diameters greater than 0.5 mm (0.02 inch). Smaller is
called drizzle.
Rain cleans the atmosphere.
Weather Modifications
• Cloud seeding: a form of weather modification,
is the attempt to change the amount or type of
precipitation that falls from clouds, by
dispersing (dry ice or more commonly, silver
iodide aerosols) into the air that serve as cloud
condensation or ice nuclei,
Storms
• Thunderstorms: A storm of heavy rain
•
accompanied by lightning, thunder, wind, and
sometimes hail.
Thunderstorms occur when moist air near the
ground becomes heated, especially in the
summer, and rises, forming cumulonimbus
clouds that produce precipitation.
Storms
• http://www.youtube.com/watch?v=1PcnCWZP7l0
Storms
• Lightning: a flash of light in the sky caused by
the discharge of atmospheric electricity from
one cloud to another or between a cloud and
the earth
• atmosphere is heated by the electrical
discharge to the order of 55,000 degrees
F
• The average lightning bolt is 6-8
miles long.
• The maximum distance you can hear
thunder is as short as two (2) miles and
seldom exceeds twelve (12) miles.
Storms
• 30 Second / 30 Minute Rule - "Flash-To-
Bang" This method suggest that when
you see a lightning flash, count the
seconds to the bang of thunder, then
divide the number of seconds by five
sound travels (5sec/mile) (3 sec/km) to
give the distance in miles from you to the
lightning.
• For example: you hear thunder 30
seconds after you see lightning, the
distance is 6 miles. Thus the reason for
the first number of the 30/30 rule.
Storms
• Tornadoes: a violent, dangerous, rotating
column of air which is in contact with both the
surface of the earth and a cumulonimbus cloud
or, in rare cases, the base of a cumulus cloud.
Storms
• Tornados:
• May and June are the peak months.
• April appears to be the deadliest month—an
average of 27 tornados. April 3-4, 1974, 148
twisters struck 13 states causing more than
300 deaths.
• Can reach speeds of up to 300 m.p.h.
Storms
• Hurricanes: 1. A severe tropical cyclone having
winds greater than 64 knots (74 miles per
hour; 119 km/hr), originating in the equatorial
regions of the Atlantic Ocean or Caribbean Sea
or eastern regions of the Pacific Ocean,
traveling north, northwest, or northeast from
its point of origin.
Storms
• Tropical low pressure.
• Greatest damage is caused by the storm surge.
Storms
• Central area is a sinking column of air called
the eye.
• 300km-600km in diameter
• Winds are most violent just outside the eye
wall.
• Can reach eight miles into the air.
Storms
• Water vapor, sucked upward around a tropical
depression, creates heat energy when it
condenses to form rain. The high-altitude heat
triggers exaggerated updrafts, which suck up
even more water vapor (warm water is the
fuel).