Module 4 Flashcards
(21 cards)
What is atmospheric pressure and how does it vary with altitude?
Atmospheric pressure is the force per unit area exerted against a surface by the weight of air above that surface. Air pressure decreases with increasing altitude
How is air pressure influenced by air temperature?
Warm air expands resulting in lower air pressure; associated with ascent of air in the atmosphere.
Cooler air contracts resulting in higher air pressure; associated with decent of air in the atmosphere
Describe the physical processes that produce vertical motions of air in the troposphere.
Hint: atmospheric pressure systems
Low pressure system:
A circulating body of air were relatively low atmospheric pressure is created as air rises away from the surface. Surface airflow converges towards low pressure systems.
High pressure system:
A circulating body of air that exerts relatively high atmospheric pressure as air sinks towards the surface. Surface airflow diverges away from high pressure systems
Describe the physical processes that produce horizontal motions of air, or wind, in the troposphere
Note: advection is the process by which air flows horizontally from areas of high pressure to areas of low pressure. Convection is vertical
Pressure systems create large circulatory systems that are interconnected by airflow. Wind is created by downdrafts and updrafts creating horizontal motion of air.
What is Coriolis force in regards to the direction of airflow?
The Coriolis force is an effect of earths rotation; it deflects a moving object to the right if it’s moving direction in the northern hemisphere and to its left in the southern hemisphere. The force increases as the speed of the moving object increases and is zero along the equator reaching maximum near the poles
Distinguish between geostrophic and surface winds
geostrophic wind blows parallel to the isobars because the Coriolis force and pressure gradient Forrest or in balance. By contrast, Hills and forests force the wind to slow down and or change direction much more. As we move higher, surface features affect the wind less until the wind is indeed geostrophic.
Describe frictional force is in regards to the direction of airflow.
Occurs at ground level and the strongest at surface, and diminishing an altitude of about 1500 m. This causes win to slow down and move at an angle across isobars
Describe the nature of air motion about centres of high and low atmospheric pressure in the northern hemisphere.
Hint: integrating all major forces
CENTRES OF HIGH PRESSURE
Pressure gradient: out, Coriolis force: clockwise, combined with frictional force: spiral out
CENTRES OF LOW PRESSURE
Pressure gradient: in, Coriolis force: counter clockwise, combined with frictional force: spiral in
Describe the nature of air motion about centres of high and low atmospheric pressure in the southern hemisphere.
Hint: integrating all major forces
CENTRES OF HIGH PRESSURE
Pressure gradient: out, Coriolis force: counterclockwise, combined with frictional force: spiral out
CENTRES OF LOW PRESSURE
Pressure gradient: in, Coriolis force: clockwise, combined with frictional force: spiral in
describe Hadley cell circulation; In regards to global atmospheric circulation
Hadley cells are the tropical convection loops. Air in the tropics is warm by year-round direct sunlight. Circulation is created by tradewinds
Describe the intertropical convergence zone (ITCZ); in regards to global atmospheric circulation
Warming creates a zone of low pressure at equator as air rises into the atmosphere by convection. Tradewinds converge into ITCZ by advection.
Describe subtropical high pressure systems STH; in regards to global atmospheric circulation
Air rising from ITC‘s he eventually six at subtropics creating zones of high pressure. Dry and warm winds diverge from STH in the Ferrel cell
Describe ferrel cells in regards to global atmospheric circulation
Convection loops that makes cool polar air with warm tropical air. Mid latitude, between 30 and 60° latitude
Describe the polar front; in regards to global atmospheric circulation
The polar front is the line of contact between the two contrasting air masses located at about 60° north and 60° south. Air removed by the Western allies is forced aloft along the polar front and is associated with mid latitude wave cyclones
Describe the polar cell in regards to global atmospheric circulation
Polar cell is a circulatory loop in the polar regions. Air flowing north word for mid latitude is forced to laugh at the polar front that sticks above the polar region producing a week high pressure system.Consists of masses of rotating, descending cold dry air that diverge towards the polar front
Describe the seasonal migration of global atmospheric circulation pressure systems
ITCZ migrates with subsolar point from the Tropic of Cancer to the Tropic of Capricorn. All large pressure systems migrate seasonally with ITCZ due to the consistent distance between them
What physical processes contribute to the generation of ocean surface currents?
Ocean surface currents are driven by winds; the transfer of energy from winds to water by friction.
Describe the nature of surface circulation in the oceans.
Larger circulation loops known as Geyer’s form as continents block the movement of water. Driven by wins associated with subtropical high pressure systems, clockwise circulation in northern hemisphere and counter clockwise in Southern
How does global oceanic circulation facilitate energy exchange?
Heat energy is exchanged by ocean circulation
Seabreeze flows from high pressure oversee to low pressure over land. Land breeze blows from high-pressure overland to low pressure oversea. This circulates heat in the air also
Describe the atmospheric and ocean circulation associated with El Nino
Reversal of the normal flow of currents and winds in tropical Pacific. Occurs every 3 to 8 years. Affects climate at margins of Pacific Ocean: changes ocean surface temperature and changes patterns of precipitation
What physical processes contribute to the generation of deep ocean currents? and describe the nature of deep ocean circulation.
Differences in temperature and salinity produces density differences and thus create deep ocean thermohaline circulation
Note: thermohaline circulation begins in the earths polar regions. When ocean water in these areas gets very cold sea ice forms. The surrounding seawater get saltier, increases in density and sinks. Wind drives ocean currents in the upper 100 m of the ocean surface
