Transcript Wind and Ocean Currents

What determines our climate?
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Climate refers to the average yearly
conditions of temperature and precipitation.
◦ Contrast with weather, the day-to-day conditions.
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The biggest difference between climate and
weather?
Weather changes frequently each day, but
climate rarely changes from year to year.
Climate is determined by several factors.
1. The latitude (north-south position) of each
region.
2. The presence of wind and ocean currents.
3. The amount of precipitation present.
4. How well heat is trapped by the
atmosphere.
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Due to Earth’s shape and its tilted axis, the
Earth does NOT receive sunlight evenly.
Sunlight is the primary means of heating up
the atmosphere. Therefore, certain parts of
Earth get a lot of direct sunlight, and are
quite warm.
Other parts of Earth get little direct sunlight,
and are quite cold.
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The polar zones are
at the very top and
bottom of Earth.
They get very little
direct sunlight; the
sun’s rays are at
very low angles.
These regions are
cold year-round.
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The tropical zone is
located around the
equator.
This region gets
direct sunlight
almost all year
round.
As such, this region
is quite warm yearround.
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The temperate zones
are located in
between the polar
and tropical zones.
The angle of sunlight
varies greatly during
the year.
As such, climate
changes from hot to
cold, based on the
seasons.
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As altitude increases, local climates will
become increasingly cold. Temperatures drop
by 6 degrees Celsius (11 degrees Farenheit)
for every 1000 meters of elevation you go up.
As a result, regions at high elevations will be
much colder than other regions at the same
latitude, but closer to sea level.
Local ecosystems are similarly affected – at
high elevations, you will see more taiga and
tundra biomes.
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4.
What is the difference between climate and
weather?
The [polar, temperate, tropical] zone(s) have
the largest range of possible climates.
The [polar, temperate, tropical] zone(s)
receive little direct sunlight.
Both Denver, Colorado and Dover, Delaware
are found at around 40⁰ north, but Denver
has a much higher elevation than Dover.
Predict their relative climates, given this
information.
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Throughout Earth, warm air and water rises,
and cool air and water sinks. This principle is
known as convection.
Convection causes air currents, better known
as wind.
Convection also causes many ocean currents.
Wind also produces ocean currents.
Currents transport heat all over Earth. Warm
currents keep climate moderate, and cool
currents make climate cold.
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The existence of air currents affects
precipitation patterns over Earth.
◦ For example, the equator receives a large amount
of solar energy, which heats a large percentage of
air. Warm air can hold a lot of moisture, but as air
rises, it cools, producing heavy precipitation.
◦ Also look at polar regions, which get relatively little
solar exposure. Since very little air is warming,
there is little moisture in the atmosphere. Polar
regions are often quite dry as a result.
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Prevailing winds are
those that primarily
move in one direction
throughout the year.
◦ Note that winds are
deflected into moving
from east to west, due
to Earth’s rotation.
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Trade winds are
found between 30⁰
north and south.
They always blow to
the west, and
towards the equator.
Westerlies are found
between 30⁰ and 60⁰
north and south.
They always blow to
the east, and away
from the equator.
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Easterlies are winds
found beyond 60⁰
north and south.
These winds blow
towards the west,
and towards the
equator.
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Areas close to large bodies of water are likely
to see a lot of precipitation.
◦ Why?
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Mountain ranges create rain shadows.
Basically, clouds are forced upward due to the
mountain range, which cools them down.
This makes precipitation much more likely,
and the cloud disappears.
As a result, the other side of the mountain is
a lot less likely to get precipitation, creating a
dry climate behind the mountain range.
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Our atmosphere contains trace amounts of
important greenhouse gases – gases that are
capable of trapping heat energy.
◦ Greenhouse gases include carbon dioxide, methane
and water vapor.
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Greenhouse gases trap heat energy, which
keeps our atmosphere warm.
◦ Without them, Earth would be 30 degrees Celsius
cooler. That amounts to 86 degrees Fahrenheit!
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However, too many greenhouse gases is not a
good thing, either!
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Tropical rain forests are found near the
equator. They are often warm and humid.
Explain why this is.
With regards to climate, what is the biggest
difference between temperate rainforest and
temperate grassland?