CLIMATE
A region’s “general” weather conditions as established over a long period of time is known
as climate.
Climate is defined by two weather variables: temperature and atmospheric moisture.
Lincoln, NE ~ 40˚N
Providence, RI ~ 40˚N
“How is it possible that two locations at the same
latitude can experience different climates?”
Climate
Regions
SUB-HUMID
SEMI-ARID
P ≅ PET
HUMID
P > PET
P = Annual Precipitation (moisture)
PET = Potential Evapotranspiration (temperature)
ARID
P < PET
Latitude
Planetary
Winds and
Pressure
Belts
Vegetatio
n
Factors
Affecting
Climate
Large
Bodies of
Water
Cloud
Cover
Elevatio
n
Ocean
Currents
Mountains
Climate Change due to
Latitude
The Earth receives maximum intensity and
fairly consistent duration of insolation
between 23 ½ ˚N and 23 ½ ˚S during its
revolution around the Sun.
Annual temperatures tend to be high and
there is a minimal variation in temperature
throughout the year.
Latitudes north of 23 ½ ˚N and latitudes south
of 23 ½ ˚S never receive direct insolation and
the duration of insolation fluctuates.
Annual temperatures tend to vary over a wide
range seasonally.
Climate Change due to
Latitude
Low
High
The location of pressure belts will alter the
moisture conditions at certain latitudes.
Low pressure belts
(convergence) are known
for rising air, cloud
development and
precipitation.
Humid-like climate
Low
High
Low
High pressure belts
(divergence) are known
for descending air, few
clouds and lack of
precipitation.
Arid-like climate
Climate Change due to Large
Bodies of Water
Land tends to heat up and cool down more quickly than water (due to specific heat).
The temperature of a location near a large body of water will be moderated by its presence near the
water (MARINE CLIMATE)
The temperatures of locations far away from large bodies of water are not affected by the presence of
water (CONTINENTAL CLIMATE).
Lincoln, NE
(CONTINENTAL
CLIMATE)
Providence, RI
(MARINE
CLIMATE)
There is no large
body of water
nearby to moderate
the temperature of
the city.
The Atlantic Ocean
helps to moderate
the temperature of
the city.
Hot summers and
Cold winters.
Cooler summers
and warmer winters.
A wide annual
temperature range.
A narrow annual
temperature range.
Climate Change due to
Prevailing Winds
Prevailing winds are generated by the
convergence/divergence of air near pressure
belts and due to the Coriolis Effect.
Storm track moving westward pick up moisture over
the Great Lakes. Cities in northwestern New York
experience “lake effect” snows and rains due to this
movement (more humid climate).
Southern California is much “more of a
marine climate” (more moderate climate
)due to the southwesterly winds blowing
off the Pacific Ocean.
Climate Change due to Ocean
Currents
Surface ocean
temperatures are a
reflection of the amount of
insolation received.
Warm ocean currents tend
to move away from the
equator. Warm ocean
currents create warm,
humid conditions for
coastal locations.
Cool ocean currents tend
to move towards the
equator. Cool ocean
currents create cool, drier
conditions for coastal
locations.
RT = Pg. 4
Some parts of
Europe (Ireland,
Iceland, England)
may be more
humid and a bit
warmer during
certain times of
the year due to
their presence
near warm ocean
currents.
The location and
pathway of ocean
currents will
change as the
amount of
insolation
received by
certain parts of
the oceans
changes during
Earth’s revolution.
As air rises it expands and cools.
Higher elevations are less likely to be
affected by greenhouse gases and the
infrared radiation being absorbed by
them.
Air
Temperature
Climate Change due to
Elevation
As air rises its temperature drops as
does its capacity to hold water vapor.
Dewpoint temperature is reached,
clouds form and precipitation follows.
Chance of
Precipitation
Elevation
Elevation
Generally speaking…..
Climate Change due to
Mountains
“The Orographic Effect”
LEEWARD
WINDWARD
Cool and humid
Warm and arid
As prevailing winds move down the
mountain:
As prevailing winds move up the
mountain:
1. Air rises, expands, and cools.
2. Dewpoint is reached; clouds form
due to condensation.
3. Precipitation occurs.
1.
2.
3.
Air descends, compresses, and
warms.
Air temperature is too high for
dewpoint to be reached.
Little to no precipitation occurs.
Climate Change due to
Vegetation
The vegetation of a region is determined by its
climate.
When the vegetation of a region is
removed, the climate will change.
The destruction of this forest will cause
the climate to change:
1.
2.
3.
4.
More insolation reaches the soil
Temperatures rise
Increase in greenhouse gases
Less infiltration of water into the soil
Deforestation
Arid
Humid
Urbanization
Climate Change due to
Cloud Cover
Ecuadorian Beach, South America
~ 0˚ latitude (equator)
Areas that are prone to cloudy
skies often experience climatic
change:
1. Less insolation strikes the
earth’s surface.
2. Slight drop in temperature.
3. Clouds absorb and reflect
insolation back into space.
The equator is NOT the
warmest spot on Earth due to
the uplift of air from the low
pressure belt. This will lead to
cloud formation and
precipitation.
“How come the equator is NOT the warmest spot
on Earth’s surface? Where is the warmest place?”
The warmest place on Earth
would be at the high pressure
belts (30˚ N and S) where air is
descending and there is a lack
of clouds.