Global wind patterns Unit 4
Wind patterns are caused by the sun, the poles get indirect sunlight and the equator gets direct sunlight, causing it to heat up more
This causes the hot, moist air in the equator to rise up and when it rises to a certain altitude it begins to expand and cool down and the water vapor turns into clouds and rain and the cold air sinks to the ground, and cool dry air falls. The cycle continues.
The earth is spinning which is why there are many convection cells, because the earths rotation pushes air masses from east to west, causing n bclockwise wind movement in the northern hemisphere and counterclockwise movement in the southern hemisphere which is called the Coriolis effect.
There are 3 convection cells in each part of the hemispheres, 0 to 30N, 0 to 30S, 30 to 60N, 30 to 60S, 60 to 90N and 60 to 90S,
At the bottom half of the hadley cells, cold air is moving towards the equator, and so are the winds, called the northeast and southeast trade winds, they move west and towards the equator.
In the bottom half of the ferrel cells, cool air is taken from the 30 degree line and is taken to the 60 degree line called the Westerlies, because they pull air from the west to the east.
The polar cells take winds from the poles and take it to the 60 degree lines, creating the easterly winds.
There is uneven distribution of the winds as water covered and land areas absorb solar energy differently and precipitate unevenly which is why there are different biomes are formed
More forests are located in low pressure areas because there is more precipitation and more deserts are located in high pressure areas because that is when cool dry air sinks which is why there is less precipitation there.
the air moves from slower to faster from 30 to 0, and from 90 to 60
The rain shadow effect
warm air starts at the bottom of the western side of a mountain, and it goes up the mountain as winds typically go from west to east here, the air parcel expands as it goes up and the pressure decreases, it turns into cold air
the cold air starts to condense out of the rains parcel, forming clouds on the windward side of the mountain range, creating rain that also falls down on the same side
the large air parcel reaches the other side, but at this point it is cold and dry because the moisture has already been taken out as rain on the opposite side
the air parcel starts to get smaller, and gets hotter again as it goes down the mountain side and pressure increases, making warm and dry air
there is more vegetation present on the windward (w) side due to this, and a more arid climate with less vegetation on the leeward side (e)
El Nino and La nina
El nino brings an abundance of fish in the Pacific Ocean and warmer waters
Trade winds are weaker and reverse from west to eat
Warm currents bring heat and precipitation to the Americas
There is suppressed upwelling off South American coasts which cause fish leave
In Australia and Asia there are cooler, drier conditions and high pressure in the western pacific while there is low pressure in the eastern Pacific Ocean
La nina brings stronger than usual trade winds
There is a rise of upwellings on the coast of South America which makes good fisheries
In Australia and Asia there is more precipitation
Thermohaline circulation
They drive ocean currents with density differences, differences in salinity
Cold water has a higher density than warm water and sinks to the bottom
Salt water has a higher density than freshwater and sinks to the bottom
sea water at the equator flows to the north pole, warming the atmosphere, but cooling the water itself, and a lot of water evaporates but leaves salt behind
decreasing temperature increases salinity
The density of the water increases and the water sinks causing deep water formation making an ocean conveyer belt
gyres are formed in the Atlantic and the pacific ocean due to trade winds that move in a clockwise rotation
in the southern hemisphere there are 3 gyres formed by trade winds but they move counter clockwise
because the ocean currents flow from the equator it starts off as warm ocean currents and so that is why the winds and the east coasts are more humid and it rains more there and they get more precipitation than the west coasts which have cold ocean currents
the gulf stream makes western Europe much warmer than other places of the same latitude
Summary: oceanic circulation is driven by differences in temperature, salinity, and wind currents, and oceanic circulation impacts temperature and precipitation in coastal areas