Transcript What Causes Our Weather?

What Causes Our Weather?
From the Sun to Our Earth!
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Global movement of matter
is driven by the properties of
water and energy
Heat Transfer:
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Radiation
Conduction
Convection
Convection is the primary
mechanism of energy
transfer in the atmosphere,
oceans and asthenosphere
What Causes Climate and Seasons
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The shape of the planet and the tilt
Milankovitch Cycles: Like a top the Earth wobbles
and the length of the elliptical orbit changes every
100,000 years as well as the tilt, causing different
latitudes to receive more or less sunlight
What are the Major Global Convection
Cells?
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Hadley Cells: Start at
equator and rise to
about 30-45 N/S
latitude (trade winds)
Rainforests form
where air rises
Deserts form where air
descends
Convection Cells
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Ferrel Cells: Exist from
30-60 degrees latitude
N/S (Westerlies)
Polar Cells: Cold, very
dry dense air (Polar
Easterlies)
Jet Streams:
Extremely fast moving
winds found at
boundaries of
convection cells
What is the Coriolis Effect?
How do our oceans affect weather?
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Trade winds created by the Coriolis Effect
apply friction to the surface of the ocean and
drag water in the same direction.
Thermohaline currents: Temperature and
salinity affect density of the ocean
consequently causing currents (cold salty
water is denser)
Twice a day the gravitational pull from the
moon causes high tides
What is El Nino-Southern Oscillation
(ENSO) ?
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Rise in temperature of 0.5 Celsius degrees more
than normal in the Eastern Pacific Ocean near the
equator, usually beginning around December (hence
the name, “Christ Child”)
Occurs at irregular intervals of 2-7 years and has
usually lasted one or two years, but has been
coming more frequently.
Disrupts global weather patterns
Triggered by Southern Oscillation
What are the Effects of El Nino
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The deeper, warmer water in the east limits the amount of
nutrient-rich deep water normally surfaced by the upwelling
process
Since fish can no longer access this rich food source, many of
them die off
What happens in the atmosphere?
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Tropical thunderstorms are
fueled by hot, humid air over
the oceans
The hotter the air, the
stronger and bigger the
thunderstorms
The east coast of southern
Africa and Australia often
experiences drought during
El Nino
Describe economic
consequences!