Transcript What is Climate? - s3.amazonaws.com

What is Climate?

Climate is the average weather
conditions of a specific region over a
long time, (tens to thousands of years)
including the range of weather
conditions (variables).
What are the Variables of Weather?

1) Temperature
 2) Air Pressure
 3) Humidity
(moisture content)

4)
 5)
 6)
 7)
Wind
Cloud Cover
Precipitation
Storms
Climate is Based on

The Water Cycle
Factors that Affect Climate
1.
2.
3.
4.
5.
6.
Latitude
Altitude (elevation)
Proximity to Large Bodies of Water
Ocean Currents
Mountain Barriers
Prevailing Winds
Latitude
The duration of insolation at low latitude
is pretty much constant, temperature
variance is small. The angle of
insolation is always quite high. Therfore,
the temperature is high as well.
 At high altitudes, temperatures vary but
remain relatively low because of the
generally low angle of insolation.

Lines of Latitude


Important to Remember
As the duration of
insolation increases, so
does the temperature.
As latitude increases,
the average yearly
temperature decreases
but annual temperature
range increases.

Lines of Latitude
Elevation

The elevation, (altitude) affects the moisture
and temperature patterns of a region. The
effects of elevation are similar to latitude.
 Lower elevations are more stable in
temperature and moisture while high
elevations have more variation.
 As altitude increases the average yearly
temperature decreases and the precipitation
generally increases.
Altitude and Elevation
Large Bodies of Water
Refer to the following website:
http://www.uwmc.uwc.edu/geography/100/
koppen_web/koppen_map.htm
Large bodies of water (large lakes and
oceans), ocean currents, and prevailing
winds modify the latitudinal climate
patterns of their shoreline areas.

Large Bodies of Water (continued)
The slow heating and cooling of large
bodies of water cause the land masses
near them to have modified
temperatures.
 Can anyone tell us why?

Large Bodies of Water (continued)
Maritime Climate
Areas on the North (West & East) coast of
the US are characterized by cooler
summers and warmer winters than would
normally be expected for that latitude.
Areas of maritime climate have small
temperature ranges.

Large Bodies of Water (continued)
Continental Climate
Inland regions (not surrounded by water)
are not directly affected by large bodies
of water. They have continental
climates. These climates are
characterized by hot summers and cold
winters.

Ocean Currents (p. 4 of your
reference table)

Ocean Currents
Maps of global winds and ocean currents look
similar. This is because the winds blowing
over the water create a frictional drag resulting
in surface currents.
The Coriolis effect (caused by earth’s rotation)
results in surface currents being deflected to
the right in the Northern Hemisphere and to
the left in the Southern Hemisphere.
Ocean Currents
Surface currents may either be warm or
cold depending upon the temperature of
the water through which they are passing
and their direction.
 Warm currents flow away from the
equator and cold currents flow towards
the equator. (Please write this on p. 4 of
your reference table)

Ocean Currents
As warm water flows away from the
equator it helps to distribute the solar
energy it has absorbed from the low
latitudes to the higher latitudes.
 Land closer to warm ocean currents tend
to be warmer than would be expected at
that latitude. Cold ocean currents have
the effect of making nearby land cooler
than would normally be expected.

Mountain (Orographic Barriers)
The overall effect on climate patterns is
called the orographic effect.
 The latitudinal climate patterns are
modified by mountains that act as
barriers to local weather systems by
interrupting the normal path of a
prevailing wind.

Mountain (Orographic Barriers)
The windward side, is the side facing
the prevailing wind. As the wind hits the
windward side of the mountain the air is
forced upward and cools by expansion
until the dew point is reached.
 Condensation then occurs and cooling
slows. These conditions cause the water
in the air to condense forming clouds
and precipitation on the windward side.

Mountain (Orographic Barriers)
The leeward side, will be drier and
warmer than the windward side. It is
said to be in the rain shadow.
 As the air rises over the mountain and
begins to descend on the leeward side, it
warms because of the compression
increasing its ability to hold moisture.

What do we see in the orographic
effect?

1.
2.
3.
4.
Windward Side
(the side that
receives the wind)
Moist Air Rises
Air Expands
Air is Cooled
Moist Air
Condenses and
forms clouds.

1.
2.
3.
4.
Leeward Side (the
side that does not
receive the wind)
Dry Air Sinks
Air is Compressed
Air is Warmed
Air is very dry (the
rain shadow effect)
The Orographic Effect (The
Mountain Effect)
Prevailing Winds
The planetary winds and pressure belts
affect moisture and temperature
patterns.
 If the prevailing wind first crosses a large
body of water before coming on land, it
will bring moisture to the land.
 If the prevailing wind crosses a large
land mass, the effect would be arid (dry).

Prevailing Winds
Prevailing Winds from the tropics
(equator) including warm ocean currents,
will bring warm moist air.
 Prevailing Winds from the polar regions
(north and south) will bring cool dry air.

What is an El Niño an La Nina??

El Niño is characterized by unusually
warm ocean temperatures in the
Equatorial Pacific, as opposed to La
Niña, which characterized by unusually
cold ocean temperatures in the
Equatorial Pacific. El Niño is an
oscillation of the ocean-atmosphere
system in the tropical Pacific having
important consequences for weather
around the globe.
What are El Nino and La Nina?


El Nino - (El Nee-nyo) is the warming
of water in the Pacific Ocean.
La Nina - (Lah Nee-Nyah) is the
cooling of water in the Pacific Ocean.
Comparison of El Nino to La Nina
El Nino Weather

Rain and flooding along
the Pacific coast
 Warm water disrupts
food chain of fish, birds,
and sea mammals
 Tornadoes and
thunderstorms in
southern US
 Fewer than normal
hurricanes in the
Atlantic
La Nina Weather

Snow and rain on the
west coast
 Unusually cold weather
in Alaska
 Unusually warm
weather in the rest of
the USA
 Drought in the
southwest
 Higher than normal
number of hurricanes in
the Atlantic
How does El Nino and La Nina
Form?

http://esminfo.prenhall.com/science/ge
oanimations/animations/26_NinoNina.ht
ml
Interesting Facts







El Nino was first discovered hundreds of years ago by fishermen
off the coast of Peru.
El Nino means "Little Boy" and was named after the Christ child,
because it usually starts around Christmas.
El Nino is officially called ENSO - El Nino Southern Oscillation.
La Nina means "Little Girl." It is also called El Viejo, which
means "old man," or an ENSO cold event.
La Nina occurs roughly half as often as El Nino
El Nino and La Nina are the most powerful phenomenon on the
earth and alter the climate across more than half the planet.
El Nino may be caused by underwater volcanoes in the Pacific.
Years of El Nino
1902-1903
1905-1906
1911-1912
1914-1915
1918-1919
1923-1924
1925-1926
1930-1931
1932-1933
1939-1940
1941-1942
1951-1952
1953-1954
1957-1958
1965-1966
1969-1970
1972-1973
1976-1977
1982-1983
1986-1987
1991-1992
1994-1995
1997-1998
?????????
Years of La Nina
1904-1905
1909-1910
1910-1911
1915-1916
1917-1918
1924-1925
1928-1929
1938-1939
1950-1951
1955-1956
1956-1957
1964-1965
1970-1971
1971-1972
1973-1974
1975-1976
1988-1989
1995-1996
1998-1999
????
Koppen Climate Zones
Lab Activity #10: Climates of an
Imaginary Continent

Please complete lab activity #10:
Climates of an Imaginary Continent.
An Imaginary Continent
HW #10, July 26, 2010
Please read pages 160-163. make a
summary on the factors that affect
infiltration and the factors that affect
runoff and stream discharge.
 For homework tonight please complete
questions 26-49 on pages 172173.
