Transcript Precipitation - Washingtonville Central School District

Section 1:
• A Cycle consisting of water
entering the atmosphere through
evaporation and returning
through condensation and
precipitation
Terms for the “Hydrologic cycle”
•
•
•
•
•
Transpiration Evaporation Evapotranspiration Condensation Ground Water -
Transpiration . . . . .
• The loss of water into the
atmosphere through the leaves of
plants (sometimes referred to as
“plant sweat”)
Evaporation . . . .
• The change of liquid water to
gaseous water vapor
Evapotranspiration . . . .
• The combined effects of
transpiration and evaporation.
Condensation
• The change of gaseous water
vapor back into the liquid phase
Ground Water . . .
• Water which is stored and moves
through the ground
Part 2: Precipitation
Precipitation requires…..
• Relatively warm moist air…
• Some agent to cause the warm moist air
to rise …..
• Expansion of the air due to lower air
pressure above it…..
• Causing the air to cool down below the
“dew point”
Precipitation terms...
• Capacity - The amount of water vapor the
air can hold at a given temperature
• (Warm air can hold more moisture than cold
air)
• Absolute humidity - The amount of water
vapor actually in the air at a given time
• Relative humidity - A comparison of the
absolute humidity to the capacity
Water will evaporate into dry air leading to a
saturated condition such as is seen in the last flask.
As the temperature falls, the capacity of the air in
the flask decreases and the water condenses
In order for clouds to form,3
basic ingredients must exist.
There must be warm moist air
There must be cooling temperatures
There must be dust particles around
which the water vapor can condense
to form cloud droplets.
As air rises, it expands
and cools. This
lowers the capacity of
the air and causes
condensation (cloud
formation) to occur.
As Cloud
droplets
strike one
another,
they
coalesce
(stick
together)
until they
are heavy
enough to
fall through
the rising
column of
air.
Mountains can block moving parcels of air and
force them upwards, cooling them by expansion.
Such cooling by expansion is called
“Adiabatic Cooling”
III. Factors which affect
climate
A. Latitude
• 1. Areas of low latitude
(near the equator) receive
high angles of insolation
(AOI) and are therefore
warmer.
2. Areas of high
latitude (near the
poles) receive low
angles of insolation
and are therefore
cooler.
3. The average AOI
is equal to the
compliment of the
latitude.
AOI = 90 - latitude
II. Altitude
• 1. As Altitude increases, the average
daily temperature decreases.
– a. The thinner blanket of air at higher
altitudes holds in less heat radiating from the
earth back into the atmosphere than does a
thicker layer at lower altitudes.
– b. Due to cooler temperatures, snow is often
found at the highest altitudes, making
temperatures even colder since white reflects
rather than absorbs heat.
C Orographic Effects
• Mountains barriers force warm moist air
to rise, making the windward sides of
mountain ranges cool and wet and the
leeward sides warmer and drier (deserts).
D. Proximity to large bodies of
water
• 1. Since large bodies of water heat up
and radiate heat more slowly than land,
they “temper” the climate. Regions close
to large bodies of water tend to have
cooler summers and warmer winters.
• 2. Inland areas tend to have more severe
temperature ranges with frigid winters
and hot summers.
The “Badlands” of interior U.S.
show evidence of extremes
The Pacific Northwest is close to
the ocean & is more temperate
E. Ocean Currents
• 1. Eastern coasts of continents tend to be
warmed by currents coming up from the
equator (driven by the Coriolis Effect)
• 2. Western coasts of continents tend to be
cooler due to the ocean currents flowing
down from the polar regions.
F. Planetary Wind Belts