Download Variation in Climate Coriolis Effect What causes seasons?

Learning Objective
• Describe the factors that influence climate.
Variation in Climate
• Climate varies around the world due to global
air circulation and ocean currents distribute
heat and precipitation differently
Agenda
• Notes
Homework
• Biomes Quiz Zero hour this week
• Air circulation is affected by:
– The uneven heating of the earth’s surface by solar
energy,
– Rotation of the earth on it’s axis,
• Seasonal changes in temperature and precipitation
– The properties of land, water, and air.
Coriolis Effect
• Air over the equator is heated, it
rises and moves toward the poles
– The earth’s rotation deflects this
movement of the air over different
parts of the planet
– As Earth rotates, its surface moves
much faster at the equator than in
mid-latitude and polar regions
• Turning of the earth creates
prevailing winds that distribute
heat and moisture in the
troposphere
– Clockwise in northern hemisphere
– Counterclockwise in the southern
hemisphere
What causes seasons?
• The earth is tilted on an
axis of 23.5°
– Various regions are tipped
toward or away from the
sun
• The variations in the
amount of solar energy
reaching the Earth creates
the seasons in the N and S
hemispheres
1
Convection Currents
Convection
Cells
• Global air circulation is
affected by the
properties of air water,
and land
• Convective currents
contribute to climatic
patterns and affect
moisture distribution
– Warm, moist air rises,
cools, releases moisture
and heat
– Prevailing winds help
distribute heat and
moisture in the
atmosphere
– Leads to the earth’s
variety of biomes
– Dense cool, dry air sinks,
picks up moisture and
heat by the Earth’s
surface
Ocean Currents
Ocean Currents
• Ocean currents are driven by a combination of
temperature, gravity, prevailing winds, the
Earth’s rotation, and the locations of
continents.
• Ocean currents influence climate by
distributing heat from place to place and
mixing and distributing nutrients
2
Ocean currents in detail
El Nino
• Trade winds created • Thermohaline
currents are created
by the Coriolis Effect
by temperature and
drag water in the
salinity changes
same direction as
– Denser water sinks,
the wind
– Major ocean
currents are
clockwise in the N
Hemisphere and
counterclockwise in
the Southern.
• Upwelling: the
vertical flow of
cold, deep water
towards the surface
– High primary
productivity and
lucrative fisheries
– As it moves it is heated,
evaporates and carry water
vapor west where it is full of
moisture and finally falls on
the tropical rainforests.
less dense water
rises
Surface winds and heating create
vertical currents
• Normally surface currents
move water east to west
from South America to
Indonesia and Southeast
Asia.
• South America has
nutrient rich, highly
oxygenated water being
pulled from the coast
causing upwellings and
great fishing.
El Nino
• El Nino year: every 3-7
years,
• Prevailing winds weaken
or reverse direction,
bringing the warmer water
and moisture to south
America instead of Asia.
• Results:
– Decrease in fish catch
– More precipitation in the
Western US or Gulf
– Australia, Indonesia and SE
Asia have drought, crop
failure, and fire.
• Video
3
The Greenhouse Effect
– Natural gases (H2O, CO2, CH4, N2O) in the
atmosphere trap radiation warming the
temperature of the Earth… makes it habitable
– Man-made greenhouse gases can enhance the
earth’s natural greenhouse effect
Topography and Local Climate
• Topographic features can affect local climates
(microclimate)
– Mountains interrupt flow of prevailing winds
– Rainshadow effect: reduction of rainfall and loss of moisture
from the landscape on the leeward side of a mountain
All the natural influences on
Earth create…
Terrestrial Biomes!
4