Transcript CLIMATE - Francis Social Studies

CLIMATE
Day vs. Night
Earth rotates on it’s axis (24 hours).
Results in day and night
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Seasons
Earth revolves around the Sun (orbits 365 days).
Results in seasons
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Cloud Cover
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Cloud Cover:
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Nightly cloud cover will result in less temperature range (like
a blanket)
Without cloud cover, heat escapes (at night), but temperature
range is very high (hot days, cold nights…the desert)
Differences in Day Length
The tilt of the earth’s axis combined with the earth’s rotation in orbit
around the sun results in different day lengths. The difference?
•In June: because of the tilt on the earth's axis, the north pole points
towards the sun and receives more hours of exposure to the sun hence
giving it longer days.
•In December: because of the tilt on the earth's axis, the north pole
points away from the sun and receives fewer hours of exposure to the sun
hence giving it shorter days.
SUN
JUNE
DECEMBER
SEASONS
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The tilt on the earth's axis and;
The revolution of the earth around the sun
These two features of the earth-sun relationship
mean that different latitudes on earth receive
different directness of light at different times.
Equinox and Solstice
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Solstice:
sun is directly over head @ 12 noon on 23.5º North
or South;
 occurs Dec 21 & June 21
 longest day of the year & shortest day of the year.
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Equinox:
sun is directly over head @ 12 noon on the equator;
 occurs Sept. 21 & March 21
 equal length of night and day everywhere on earth.
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Tropics vs. The Poles
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The tropics are located between 23.5˚ north and 23.5˚
south(Cancer and Capricorn)
The further you move away from the tropics the more severe the
seasons.
The length of day varies more the further you move from the
equator.
When light hits the earth towards the poles it is on a
severe angle which decreases the intensity of heat.
How the Sun hits the Earth
Greenhouse Effect
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A good thing?
In moderation of course; moderates our
temperatures
Without we would have extreme variation of
temperatures between day and night
Atmosphere reflects and absorbs about 50% of radiant
energy
Without atmosphere, planets have nothing to hold heat in
(like the glass in a greenhouse… consequently the nights
are not as cool)
Latitude and Temperature
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The closer we get to the equator, the warmer it
gets
“The further south one goes the warmer it gets”
(FALSE). Once we went far enough south to go past the
equator the temperatures would start getting colder again.
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As latitude increases, temperature decreases
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Other Factors
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Prevailing Winds
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Regular, predictable, normal wind direction. They are caused by
global convection cells in the earth's atmosphere.
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Ocean Currents
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The biggest factor besides the sun. If the water is warm, the
temperatures will be more moderate.
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Altitude
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the higher the altitude, the cooler it will be.
Rate is about 1˚ per 100m
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Altitude
WIND
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Winds Blow From High Pressure to Low
Pressure
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Any real examples of this at work?
Air inside a balloon. If left untied the air will escape the high
pressure of the balloon and create a wind blowing from high
pressure (inside the balloon) to relatively low pressure (outside the
balloon).
High and low pressures in the earth’s atmosphere are
responsible for wind.
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High vs. Low Pressure
Low Pressure:
Usually a result of “heating”
 High Pressure:
Usually a result of “cooling”
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Sea Breeze/Land Breeze
What heats faster; land or water?
 When do things warm or cool over the course of 24
hours?
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During the day the land heats much faster than the water;
Consequently the air over the land heats and rises (low pressure) while
the air over the water/sea is relatively high;
Wind blows from the high pressure to the low pressure
Hence the name 'sea breeze'—the wind is blowing off the sea.
During the Day
Convection Cells
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The global convection cells are created because
of the differential heating of the earth's surface.
Alternating high and low pressure belts result from
the convection cells.
You want real results?
Convection Cells
The results?
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Every desert in the world is found at a similar latitude
Every rainforest of the world is found at a similar
latitude.
Coincidence?
Types of Rain
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Three types of rainfall:
1.
2.
3.
Relief Rain
Convectional
Frontal / Cyclonic Rain
Rain. Period.
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hot air rises
warm moisture-laden air cools at higher altitude
cool air holds less moisture;
consequently clouds condense and rain falls.
Relief Rainfall
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Moisture laden air blows off the sea;
Air is forced up by mountains (high relief)
Most rain falls on the windward side of the relief
Leeward side is often in a dry rain shadow because the
moisture has all been lost.
Relief Rainfall
Convectional Rainfall
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Usually occurs in hot areas like tropics or
continental summer (Winnipeg thunderstorms)
sun heats the earth causing large amounts of
water to evaporate
Then what?
Remember RAIN.PERIOD. Check it out!
Convectional Rainfall
Frontal / Cyclonic Rainfall
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Warm moist air meets cold air
Warm air is less dense & is forced up over the
cooler, more dense air
Then What?
Fall/spring/some summer Winnipeg rains
Frontal Rainfall
Ocean Currents
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Permanent horizontal movement of surface
water (the top 100m)
It is unusually cold or warm, when compared
with the surrounding water
Analogy:
Sun=CEO of climate
Ocean Currents=BOSS of climate
Where do they go?
Where would you expect cool currents to start
from?
Where would you expect warm currents to start
from?
How do currents create balance in the world?
Warm and Cold Currents
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Cold ocean currents: move water towards the equator.
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For example the Humbolt or Peru Current carries cold water from
Antarctica toward the equator.
Another example is the Labrador Current which carries cold water from the
Arctic Ocean.
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Warm ocean currents: Move water away from warm
equatorial regions.
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For example the Gulf Stream moves warm water from the Gulf of Mexico
northeast toward England.
Another good example is the Japanese current which moves warm water from
Japan northeast towards Vancouver.
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Ocean Currents & the Affect on
Climate
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Affect of cold ocean currents
Cools the summer temperature;
Reduces precipitation; cooler air holds less moisture.
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Affect of warm ocean currents
Warms the winter temperature;
Increases precipitation; warmer air holds more moisture.
El Nino
Continentality
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Temperature range: the difference between the
highest and the lowest average monthly temperatures of a
region.
 What helps creates this range in this case?
Proximity to ocean (or larger body of water)
 Large or high temperature range: extremes of temperature, hot
summer, cold winter (Winnipeg).
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Small or low temperature range: moderated temperature, warm
summer, cool winter (Victoria)
Continental vs. Maritime Climates
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As distance from the ocean increases,
annual temperature range increases.
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Continental climates experience greater extremes of temperature than coastal
climates at the same latitude.
The plains region of Saskatchewan, for example, experience a continental
climate. The winter temperatures are very cold, and the summer temperatures
are fairly hot. Range could be from: -40° to 40°C
Close to the ocean, Victoria experiences a much more moderate climate.
Range is from: -5° to 25°. Not too cold, but at the same time, not too
hot in the summer.
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Climate Graphs
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Give us a yearly climate snap-shot of a given
place
Temperature will always be shown with a line
graph
Precipitation will always be shown with bar
graphs
Maritime
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Scotland….
Continental
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Winnipeg
Tropical Climates
All Tropical Climates have average
temperatures over 18˚C every day
 All Tropical climates can be divided into:
a) Tropical Wet
b) Tropical Wet and Dry
 Almost all of the tropical wet / wet & dry climates are
located between the tropic of cancer and the tropic of
Capricorn (23.5˚ N and S).
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Tropical Wet Climate
Tropical Wet : heavy rain all year due to hot temp & resulting convectional rain.
Tropical Wet and Dry Climate
Tropical Wet& Dry: very heavy summer rain & very
dry winter due to seasonal shift in prevailing winds.
(monsoon regions)
Dry Climates
All Dry climates receive less than 500mm
precipitation annually.
 Dry Climates can be divided into:
a) Arid
b) Semi-Arid
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more evaporation than precipitation = water deficit.
 There is little vegetation & it is often windy
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Arid or Desert Climates
 Arid Climates: occur mostly between 10-30˚N &
10-30˚S and receive 10-250mm rain annually.
Semi-Arid Climate
 Semi-arid Climates: are transition zones between
Desert & Forest. They receive 250-500mm rain
annually which is often enough to support
grasses but not forests.
Temperate Climates
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Usually in higher latitudes (above 30˚ N and S)
Temperate Climates can be divided into:
a)Temperate Mild Climates occur in both
hemispheres
b)Temperate Cold Climates only occur in the
northern Hemisphere. (Winnipeg)
The distinguishing feature on a climate graph is the
temperature line (yearly average Temp.)
Temperate Climates
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Temperate Mild Winter
 Temperature varies with seasons
 Mid Latitudes
 Mild winter
 Summer temperatures vary but winters are warmer
than –3ºC
Temperate Cold Winter
 Temperature varies with seasons
 Mid-high Latitudes
 cold winters
 Summer temperatures vary but winters are colder
than –3ºC
Temperate Climate
Polar Climates
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Polar climates are distinguished by their
extremely low winter temperatures and low
summer temperatures.
Polar Climates can be divided into:
Tundra: summer temperature never above 10˚C
 Ice Caps: summer's average monthly temperature is
never above 0˚C
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Polar Climate
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Monsoons
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A sudden wet season in the tropics. Notice the
difference between the annual rainfall of some
“rainy” places directly influenced by monsoons
India’s Monsoons
India’s Monsoons
India’s Winter Monsoon
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Continental Asia cools & high atmospheric pressure results;
Wind blows southward towards the low pressure over Indian
ocean;
Very little rain or dry season results because the wind is blowing
over dry land and does not pick up moisture.
India’s Summer Monsoon
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Continental Asia heats up & low atmospheric pressure results;
Wind blows northward towards the low pressure over India;
Tremendous rains result because the wind is blowing over the
warm Indian Ocean.
India’s Monsoons
Affect on People
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Tourism in the tropics is very important. During monsoons, travel is not safe, even
prohibited in some cases (Malaysia’s East Coast)
Severe flooding
Economy suffers (fishing, tourism, etc.)