Transcript Met112lecture4 - San Jose State University

MET 112 Global Climate Change - Lecture 4
Controls on Climate
Dr. Eugene Cordero
San Jose State University
Outline
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Energy balance: a latitudinal perspective
Seasons
Atmospheric circulation; quick view
Climate game
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Definitions
 Insolation – Incoming solar radiation
 Solstice – day of the year when the sun shines
directly over 23.5°S or 23.5°N
 Equinox –
days of the year when the sun shines
directly over the equator
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Sun angle
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Sun angle (2)
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What influences incoming solar
energy?
 The Sun’s angle of incidence:
– Lower sun angle, less incoming energy
– Higher sun angle, more incoming energy
 Length of time the Sun shines each day:
– Summer season, more sun hours
– Winter season, less sun hours
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Why do we have seasons?
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What month do you think this graph represents?
a) December b) March c) June d) September
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What month do you think this graph represents?
December
March
June
September
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Review questions
 On June 21st, at what latitude is the sun directly
overhead at noon?
 On September 22nd, at what latitude is the sun
directly overhead at noon?
 How many hours of daylight are present at the
South Pole on February 20th?
 Where would you expect to have longer days;
45 ° N on June 21st or 50°S on Dec 21st?
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On June 21st, at what latitude is the sun
directly overhead at noon?
Equator (0)
23.5°N
23.5°S
90°N (north pole)
90°S (south pole)
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Where would you expect to have longer days;
45 ° N on June 21st or 50°S on Dec 21st?
45°N
50°S
They are the same
Impossible to tell
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On September 22nd, at what latitude is
the sun directly overhead at noon?
Equator (0)
23.5°N
23.5°S
90°N (north pole)
90°S (south pole)
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How many hours of daylight are present
at the South Pole on February 20th?
0 hours
6 hours
12 hours
18 hours
24 hours
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Earth’s energy: latitudinal
perspective
 A majority of the sun’s energy enters the Earth
system in the tropics.
 The tropics thus becomes quite warm, while the
poles relatively cool.
 The atmosphere attempts to bring the tropics
and high latitude into equilibrium
– Weather systems ultimately act to bring
warm air to higher latitudes and cold air
to lower latitudes.
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Annual Surface Temperature
Questions
 Indicate the warmest and coldest areas of the
Earth.
 Consider the temperature at 60N latitude.
Indicate on the map the coldest and warmest
places at 60N.
 What is the temperature difference between
these locations
 What factors might explain this temperature
difference?
 Why is there not a similar difference seen at 60S?
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Annual Surface Temperature
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Climate controls:
Latitude/Mountains
 Latitude
– Higher latitude climates are generally
(cooler/warmer)
– Lower latitudes climates are generally
(cooler/warmer)
 Mountains
– Higher altitudes climate are generally
(cooler/warmer): cooler temperatures
– Windward side of mountains are generally
(cooler/warmer) and (wetter/drier), than
leeward side
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Climate controls:
Latitude/Mountains
 Latitude
– Higher latitude climates are generally
(cooler/warmer)
– Lower latitudes climates are generally
(cooler/warmer)
 Mountains
– Higher altitudes climate are generally
(cooler/warmer): cooler temperatures
– Windward side of mountains are generally
(cooler/warmer) and (wetter/drier), than
leeward side
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Controls on Climate
 Seasonal temperature and precipitation patters
are generally attributable to:
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Latitude
Mountains and highlands
Land and water location
Prevailing winds
Pressure and wind systems
Ocean currents
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Controls on Climate: Oceans
 Ocean Temperatures
– Coasts of continents are affected by ocean
temperatures: Generally less temperature
extremes compared to interior of continents
– Cold oceans:
generally produce cooler/drier conditions
– Warm oceans:
generally produce more warm/humid conditions
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Cold ocean
Warm ocean
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Dry
Humid
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Controls on Climate: Pressure
systems
 Rising and sinking motion associated with low
and high pressure affects climate
 Areas where pressure seasonally low,
–
Tropics: rainy
 Areas where pressure seasonally high,
– Subtropical high (30N/3OS): warm and dry
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January Average sea-level Pressure and surface wind pattern
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July Average sea-level Pressure and surface wind pattern
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A_B_D_ - let’s check out clicker id’s out
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Climate Game
Names ___________________________
 Match the city with the corresponding climatology
by indicating the appropriate letter
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Sacramento, California (38°N)
Phoenix, Arizona (33°N)
Denver, Colorado (40°N)
Iquitos, Peru (4°S)
Mobile, Alabama (30°N)
Winnipeg, Canada (50°N)
Fairbanks, Alaska (65°N)
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City A
Sacramento, California
Phoenix, Arizona
Denver, Colorado
Iquitos, Peru
Mobile, Alabama
Winnipeg, Canada
Fairbanks, Alaska
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City B
Sacramento, California
Phoenix, Arizona
Denver, Colorado
Iquitos, Peru
Mobile, Alabama
Winnipeg, Canada
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City C
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Phoenix, Arizona
Denver, Colorado
Iquitos, Peru
Mobile, Alabama
Winnipeg, Canada
Fairbanks, Alaska
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City D
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Phoenix, Arizona
Denver, Colorado
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Mobile, Alabama
Winnipeg, Canada
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City E
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Phoenix, Arizona
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Mobile, Alabama
Winnipeg, Canada
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City F
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