|The temperature of air changes in a zig-zag
fashion in various layers.
For global circulation and "weather" only the troposphere is important.
|CIRCULATION OF AIR -
hot air rises
Hot rising columns of air is always seen at the equator. Here is an example of hot rising air in Wisconsin or Michigan. The rising hot air sets up the condition where the cooler air over water moves inland.
|CIRCULATION OF AIR -
the rotation of the Earth causes winds
-- air flowing toward the equator curves toward the west producing an easterly wind (west toward east) while air flowing toward the poles curves toward the east producing a westerly wind (east toward west).
-- this causes the flow pattern to break into cells.
Instead of flowing all the way between the equator and the poles, the air sinks at latitude 30^0 and rises at latitude 60^0 producing three cells in each hemisphere.
in the northern hemisphere this produces
northeasterly winds (the northeast trade winds) between the equator and 30^0 north latitude.
northwesterly winds between 30^0 and 60^0 north latitude,
northeasterly winds between 60^0 north latitude and the poles.
the same is true in the south, except reversed
|"Low pressure systems are generally very warm due to the fact the warm air rises making the system it is on having low pressure. This is generally the reason for storms and Tropical cyclones."|
|"High pressure systems occur often
when there is an uneven heating of the ground, causing the hot air to rise
and spread out. This rising air creates an air 'void', or a low-pressure
system in the area above the ground. However, when the air cools and
sinks back down to the ground, a high-pressure system is created. High
pressure systems are associated with clear, cool weather."
|THE DOLDRUMS and HORSE LATITUDES
- Where the air is mainly rising or falling, near the equator, 0o, 30o, 60o, and the poles, the winds are light and variable.
sailing ships the region near the equator, 0o, was called the doldrums and the regions near 30o north and south latitude were called the horse latitudes.
- sailing ships must take wind direction and still air areas into account
-- story. standing dead trees at 30o, 60o
|- local climate is strongly affected by
local continental features.
- where winds "go east" like in the US, high mountains force moist air up where it cools and drops rain so the coastal area is wet
- dry air coming back down the eastern slopes of produce the deserts and dry plains
the eastern US is affected by air flowing up from the Gulf of Mexico and south from northern Canada.
"Warm, humid air flows from over the Pacific
Ocean east across the mountains of the western USA. As the wind pushes
the air over the mountains, it cools and much of the humidity in it condenses
to form clouds, rain and snow that fall on the western slopes of the mountains.
|BIOLOGICAL CYCLES OF OXYGEN,
NITROGEN AND CO2 AKA AIR
Draw a picture and discuss the circulation
of the atmosphere for a single cell at the equator. How does this
circulation affect climate and rainfall in the adjacent areas? What
drives this circulation?
What is the coriolis force, what causes the coriolis force, how does it change the single cell model of air circulation?
Discuss the winds and climate at the equator.
What happens to air flow at the Doldrums and Horse latitudes?
What causes high pressure systems? What causes low pressure systems?
What causes belts of desert that surround the earth at certain latitudes?
Discuss how local continental features affect weather/climate using the west and east side of the Rocky Mountains as an example.