Transcript Climate Controls and climates

Climate Controls
Why does temperature vary so much in the world?
The answer: O LAMPNAS!
or USE
PSALMON
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1) Ocean Currents: can either warm or cool a coastal area by approximately two degrees
Celsius.
Warm and cold ocean currents circulate through out the world’s oceans and these have a
heating/colling effect
Gulf Stream (warm current) warms areas in Europe (Britain) making the climate
moderate
Cold Ocean Currents will create dry regions around the globe=Atacama desert in Chile is
a result of cold ocean currents as the bring dry air from the see over land
Note: Winds produce currents.
eg Los Angeles: California Current (cool)
Halifax: Gulf Stream Current (warm)
Pages 147 to 148 in Planet Earth: A Physical Geography
2) Latitude: the further north you go in the northern hemisphere,
the colder it gets.
Why?
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a) Curvature of the earth: the sun strikes the earth in a very
concentrated fashion at the equator, whereas at the poles,
the sun's rays are much more spread out.
b) The Seasons: spring, summer, fall, and winter result
in different amounts of heat coming to the earth. This is
caused by the changing position of where the sun is directly
overhead on the earth's surface during the year and the tilt
of the earth's axis.
i.e. Mar. 21 (Vernal Equinox) and Sept. 21 (Autumnal
Equinox): the sun is directly overhead at the equator.
Dec. 21 (Winter Solstice): the sun is directly overhead at the
Tropic of Capricorn (23.5 S).
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June 21 (Summer Solstice): the sun is directly overhead at the
Tropic of Cancer (23.5 N). Lower latitudes receive more
sunlight – warm climates with small temperature ranges
Higher latitudes = rays of sun are more spread out= colder
climates more temperature extremes = evident in poles.
Further Information: Pages 137 to 140 in Planet Earth: A
Physical Geography
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http://www-class.unl.edu/geol101i/15a_climate.htm
3) Altitude: the higher you go up, the colder it gets.
Why? Less dust, greenhouse gases, water vapour, etc. to trap heat coming up from the
earth's surface.
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Environmental lapse rate: 1 deg. C drop for every 150 m rise or 6.4 deg. C drop for
every 1000 m
As elevation increases – temperature decreases (think of going up a mountain)—1
degrees for every 150 meters of elevation.
Air becomes thinner cannot conserve (keep) heatthat is why pressure decreases with
elevation.
further information: http://en.wikipedia.org/wiki/Environmental_lapse_rate
Pages 152 to 153 in Planet Earth: A Physical Geography
4) Mountain Barriers: impede the movement of cold air masses. This is due to the
fact that cold air is dense and generally stays near to the ground.
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Air is forced to rise on the windward side of mountain causing precipitation
Leeward side the wind falls creating clear, dry conditions=rain shadow
eg Vancouver is shielded from most Arctic air masses by the Rockies and Coast
Mountains.
Mountains can also result in warm winds descending down slope
eg a chinook: a warm wind that undergoes adiabatic heating. This westerly
wind is dry and blows down the eastern side of the Rockies affecting cities such
as Calgary.
Further Information: Pages 153 to 154 in Planet Earth: A Physical Geography
5) Prevailing Winds:
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Low pressure around the equator and mid-latitudes (30-60 degrees) = have much precipitation
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High Pressure around sub tropical (30 N/S) and poles (90 N/S) have little rainfall.
Mid-latitudes are changeable and they have precipitation in the winter (low pressure) and high
pressure in the summer (clear-sunny skies)
Further Information: Pages 141 to 146 in Planet Earth: A Physical Geography
6) Nearness to Water or Continentality: the closer a city is to a large body of water, the
more moderate will be its temperatures (i.e. maritime climate), whereas the further
away a city is from the water, the greater the temperature extremes (i.e. continental
climate).
• Locations near water=wetter/moderate
• Interior (Continental) locations are drier and have more temperature extremes
• Ex. Gobi Desert in Mongolia/China (dry interior conditions)
Try to think of differences in climate between a place like Vancouver and Winnipeg…
Further Information: Pages 149 to 151 in Planet Earth: A Physical Geography
7) Amount of Cloudiness:
Cloudy conditions generally produce cooler days (i.e. less solar
radiation is able to reach the earth) and warmer nights (i.e.
clouds act as a blanket to keep in heat emitted by the earth)
- the amount of cloudiness is dependent upon the air pressure
Low Air Pressure: cloudy conditions
High Air Pressure: clearer conditions
8) Slope of the Land (also known as Aspect)
- largely a micro-climatic control
Direction a slope faces
In the northern hemisphere:
• south facing slopes are drier (more sunshine)
• north facing slopes are wetter and have less sun
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See fig. 17.3 in SOVIO
Climates of the World
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Introduction
Weather refers to the current state of the atmosphere. Climate involves long term averages of
temperature and precipitation.
In the previous unit, you learned about the three processes of precipitation (convectional,
orographic, and frontal) as well as factors that influence temperature (i.e. O LAMPNAS). Keep
these in mind, as you progress through this unit.
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2103/es2103page01.cfm?chapter_no=visualization
http://www.blueplanetbiomes.org/climate.htm (it’s the best)
http://www.uwsp.edu/geO/faculty/ritter/geog101/uwsp_lectures/lecture_climate_class.html (this is an unbelievable website
http://www.learner.org/resources/series78.html?pop=yes&vodid=482602&pid=312# (free videos)
http://www.worldbook.com/wb/Students?content_spotlight/climates/about_climates
http://www.kbears.com/climates.html (childish, but education!)
http://members.aol.com/bowermanb/weathergames.html (games) great website!
Tropical Climates
A) Tropical Climates: Warm temperatures all
year.
1) Equatorial or Tropical Wet
Climate Explanation:
• - low latitude: direct rays of the sun overhead
allows for maximum heating resulting in
• warm temperatures and active convectional
precipitation
• - near the equatorial Low pressure zonePrevailing Winds
Locations:
Brazilian Rainforest
Indonesia
Zaire (equatorial portion of Africa)
2) Tropical Wet and Dry
Climate Explanation:
• - similar to Equatorial in terms of temp.
• - active convectional precipitation
for part of the year and then dry for
the remainder due to the influence of
the subtropical High anchored at 30 N or
S – Prevailing Winds and Latitude
A Baobab tree, with its thick trunk and large edible fruit, Dakar, Senegal.
Locations:
Ibadan, Nigeria
Sudan
Mexico
Bombay, India
3) Monsoon
Climate Explanation :
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- in "Summer", tremendous heat over the Indian
subcontinent forms a Low while the ocean which
heats up slower maintains a High. Therefore,
wind blows onshore from
High to Low bringing tremendous rainfall
(Note: Notice the scale is different for the
Monsoon climate graph in order to
accommodate the tremendous precipitation
from June to September.)
• - in "Winter", the land cools down quicker than
the ocean over northern India and Nepal.
• Therefore, a High forms over the land and a Low
over the ocean. The Wind blows offshore
bringing much drier conditions.
Note: In order to differentiate between a Monsoon climate
and a Tropical Wet / Dry climate, look at
the precipitation amounts in the summer months. There is
considerably more for the Monsoon
climate such that the scale is changed to accommodate the
larger quantities of precipitation.
Locations:
India
Thailand
B) Arid Climates: Low precipitation all year.
1) Tropical Desert (Hot Desert)
• Climate Explanation:
• - low latitude (20 to 30 N & S), therefore
hot when sun directly overhead
• i.e. June, July, and Aug. in the northern
hemisphere
• - dry due to influence of subtropical High
pressure area at 30 N or S
high pressure – Sahara Desert (Northern
Africa)
cold ocean currents – Atacama Desert (Chile)
• − continentality – Gobi Desert (China)
• − rain shadow – Mojave Desert
(California) -
Cairo, Egypt
Locations:
Southern California
Baja, Mexico
Northern Africa
Middle East
2) Cold Desert, Arctic
Climate Explanation:
• - under the full influence of the
Arctic or Antarctic High Pressure
Area, therefore dry
• - high latitude (i.e. > 65 N or S),
therefore sun's rays spread out
resulting in little heating
Scientist exploring Taylor Glacier in McMurdo Sound, Victoria Land, Antarctica
Locations:
Northernmost Portion of Russia
Greenland
Northernmost portion of Canada-Nunavut
C) Coastal Climates : Moderate
temperature ranges with moderate
precipitation.
1) Cool Climate - Moderate Winter or
Maritime (eg Vancouver and
London, England)
Climate Explanation :
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- orographic precipitation caused by
coastal mountain barrier and onshore
wind flow
- frontal precipitation during Fall, Winter,
and Spring due to meeting of different air
masses from the north and south
- drier in Summer due to High air pressure
- nearness to water moderates
temperatures
PSALMONS-Prevailing Winds, Nearness to
water, Mountain Barrier, Ocean Currents
Coniferous forest of western Oregon.
Locations:
You better know this one!
BC
British Isles – Northern Europe
2) Mediterranean
Climate Explanation :
• - 30 to 40 N or S on the west side of continents
• - influence of High pressure at 30 N or S keeps conditions quite clear and dry
especially in Summer
• - some frontal precipitation in Winter
• - found in places such as Spain, Greece, Italy and Northern California
(Sacramento)-cold ocean current for this area
• During the winter the subtropical high shifts to the south and its influence is
replaced by the Westerlies associated with the subpolar low. During this
period, mT, mP, and cP air masses invade the climate. Midlatitude cyclones
formed in the Westerlies bring much needed precipitation during the winter.
Locations:
Sacramento, California (Northern Cali.)
Spain
Greece
3) Warm Climate – Wet –Humid Subtropical (in Sovio)
Climate Explanation :
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- warm / moist tropical air brings convectional precipitation
- frontal precipitation also possible
- threat of hurricanes from off the ocean particularly on the coast
- threat of tornadoes eg tornado alley USA
- low latitude: 25 to 40 N or S on east side of continents-extreme
temps and lots of ppt-similar to equatorial, but further up north
New Orleans, USA
Deciduous Forest
Locations:
New Orleans
Florida
Japan
C) Continental Climates : Extreme temperature ranges
with low precipitation.
1) Humid Continental (in Sovio)—Cool Climate
Severe Winter in Mleziva
Climate Explanation :
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- being further inland results in greater temperature
extremes with cold winters and warm summers Recall:
land heats up and cools down faster than the ocean
- most precipitation occurs in Summer in the form of
convectional precipitation
- frontal precipitation is also possible as cold air
masses from the north meet warm on from the south
- threat of tornadoes in the southerly part of this zone
particularly on the Great Plains
Ottawa, Canada
Coniferous Forest
Locations:
Prairies (Saskatchewan/Manitoba)
Ottawa
2) Warm Climate – Dry
Climate Explanation :
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- places lie on the leeward or
rainshadow side of mountain barriers,
therefore it is clearer
and drier
- some convectional precipitation in
the heat of summer
- inland, therefore more extreme
temperatures with warm summers
and cool winters but
not as cold as the previous zone
because further south
Locations:
Prairies (Alberta)
Ukraine (in between-Cool Climate-Severe Winter and Warm Climate/Dry