CH 6 Flashcards
What happens to pressure and density when altitude increase?
they decrease
What exactly is “thin air”?
it is because of less oxygen, so fewer molecules.
What is acute mountain sickness?
Mountain climbers experience this sickness
Dense and pressure in cold air vs warm air
Warm air has less density and pressure compared to cold air
Mercury barometer
He sealed the glass tube at one end, filled it with mercury, and inverted it into a dish containing mercury, at which point a small space containing a vacuum was formed in the tube’s closed end. The average height of the mercury depended on the weather, the mass of surrounding air was exerting pressure on the mercury in the dish and thus counterbalancing the weight of the column of mercury in the tube.
Aneroid barometer
Aneroid means “no liquid”, Imagine a small chamber, partially emptied of air, which is sealed and connected to a mechanism attached to a needle on a dial. As the air pressure outside the chamber increases, it presses inward on the chamber; as the outside air pressure decreases, it relieves the pressure on the chamber—in both cases causing changes in the chamber that move the needle
2 properties of wind are:
speed and direction
Instruments for measuring wind speed and direction:
speed = anemometer
direction = wind vane
Beaufort wind scale
ships used to use this to find wind speed
the four forces which determine speed and direction of winds:
1- gravitational forcer
2- Pressure gradient force
3- Coriolis force
4- Friction force
gravitational force
The gravitational force counteracts the outward centrifugal force acting on Earth’s spinning surface and atmosphere. Without gravity, there would be no atmospheric pressure—or atmosphere, for that matter
Pressure gradient force:
Drives air from areas of higher barometric pressure, to areas with lower barometric pressure thereby causing winds.
Coriolis force:
A deflective force that makes wind traveling in a straight path appear to be deflected in relation to earth’s rotating surface. An example of this force is how the flight path changes from country to country, the path would have stayed straight if earth was not rotating.
Factors that contribute to the Coriolis force:
earth’s rotation
deflection occurs regardless of the direction the object is moving
deflection increases with speed of object
Isobar:
An isoline ( a line which there is constant value) plotted on a weather map to connect points of equal pressure. The spacing between isobars indicates the intensity of the pressure difference, or pressure gradient
More space between isobars means less winds
Less space between isobars means more wind
pic below:
https://plus.pearson.com/eps/pearson-reader/api/item/dad600a5-17dd-4611-bbed-0a368ab01d61/1/file/9780134853543_et2_dccsb_l2_redserif_default/OPS/images/fg06_06.png
Geostrophic winds:
flow parallel to isobars because they balance the pressure force and the Earth’s rotation, instead of going directly from high to low pressure.
What causes geostrophic wind flows in the upper atmosphere?
Surface friction interfering with the pressure gradient and the Coriolis force
Anticyclone:
wind spiral clockwise outwards from a high pressure area
air moves away from the center of an anticyclone
cyclone:
wind spiral anticlockwise into low pressure area
surface air flows toward the center of a cyclone, it converges and moves upward (stormy weather)
https://plus.pearson.com/eps/pearson-reader/api/item/dad600a5-17dd-4611-bbed-0a368ab01d61/1/file/9780134853543_et2_dccsb_l2_redserif_default/OPS/images/fg06_09.png
Atmospheric circulation is categorized at three levels:
1- primary circulation: consisting of general worldwide circulation
2- secondary circulation: consisting of migratory high-pressure and low-pressure systems
3- tertiary circulation: including local winds and temporal weather patterns
Meridional flows:
Winds that move principally north or south along meridians of longitude
Zonal flows:
winds that move east or west along parallels of latitude
Hadley cell
Responsible for tropical wind circulation
intertropical convergence zone
area where trade winds meet
Trade winds
The winds converging at the equatorial low
Rossby waves:
occur along the polar front where cold air meets warm air, and brings cold air southwards, with warm air moving northwards
Jet streams:
irregular, concentrated bands of wind occurring at several different locations that influence surface weather systems. They weaken during the hemisphere’s summer and strengthen during its winter as the streams shift closer to the equator
Monsoons:
Seasonally shifting wind systems which bring rain during the summer months
Land and sea breezes
The different heating characteristics of land and water surfaces create these breezes
How do breeze occur?
Warm air is less dense, it rises, creating a lower-pressure area that triggers an onshore flow of cooler marine air to replace the rising warm air. At night, land radiates energy faster than the water, so the cool air above the land subsides to the shore of the water where the lower pressure area over the warm water
https://plus.pearson.com/eps/pearson-reader/api/item/dad600a5-17dd-4611-bbed-0a368ab01d61/1/file/9780134853543_et2_dccsb_l2_redserif_default/OPS/images/fg06_17.png
Kabatic winds
elevated land or highland is where they are formed. Layers o air at the surface cool and become more dense, then flow downwards the slope. They are not related to the pressure gradient
What is the driving force for ocean currents?
frictional drag of winds
western intensification:
Trade winds push ocean surface waters westward along the equator, forming equatorial currents. These currents stay near the equator because the Coriolis force is weak there. As the water reaches the western edges of the oceans, it “piles up” against the eastern coasts of continents, creating a rise in water level of about 15 cm.
Upwelling currents
occur when surface water is swept away from a coast by divergence (Coriolis force) or offshore winds
Downwelling currents
In areas where water accumulates, like the western end of an equatorial current or near Antarctica, the excess water sinks
Thermohaline circulation
different temperatures and salinity that produce density differences which are important to the flow of deep currents
Why is climate change effecting THC?
Ocean surface water become “freshened” when water freezes since it releases salt when it does, and so after it melts again the water is fresh and salt free. Climate change is accelerating this process because when the increasing glacial, and ice sheets melt, there is more less dense and fresh water floating over the dense and salty water that was already there. If a significant amount of fresh water enters the North Atlantic, it could lower the seawater density enough to stop downwelling, potentially disrupting the thermohaline circulation
Southern oscillation
The shifting of atmospheric pressure and wind patterns across the Pacific. Pressure patterns and surface ocean temperatures shift from their usual locations in the Pacific, higher pressure than normal develops over the western Pacific, and lower pressure develops over the eastern Pacific. Trade winds moving from east to west also change from west to east.
La nino and La nina
warm phase and cold phase
