Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
35 Cards in this Set
- Front
- Back
|
What is the primary objective of studying atmospheric circulation in a planetary scale?
|
To understand the physical mechanisms that maintain the balance of energy.
|
|
|
The spatial distribution of air is characterized by...
|
Differences in atmospheric pressure.
|
|
|
Define air pressure...
|
Air pressure is the force exerted by a column of air above a surface. Air pressure is higher at lower altitudes and lower at higher altitudes.
|
|
|
Unequal heating of the earths surface owing to the earth's ___ ___ causes the unequal distribution of energy===>unequal distributions of temperature===>unequal distributions of pressure.
|
axial tilt
|
|
|
Define and descibe a cyclone...
|
A cyclone is a zone of extremely low pressure. In the northern hemisphere, as air enters an area of low pressure, the coriolis force bends the air to the right of its path. This creates a counter-clockwise rotation around the low and convergence near the center of the system (clockwise rotation in the S. hemisphere). As the air collides near the center it is forced aloft where it then diverges, thus mainting a low pressure system at the center.
|
|
|
Define and describe an anticyclone...
|
An anticyclone develops around an area of high pressure. In the northern hemisphere, air diverges away from the center in a clockwise direction, because the coriolis force bends the air to the right of its path.
|
|
|
Explain how differences energy distribution, and therefore differences in pressure, lead to the migration of air masses.
|
Unequal heating of the earth's surface causes unequal distributions of temperature over the earth's surface. In general, air becomes cooler as we move farther away from the equator. Differences in temperature lead to the development of a pressure gradient that follows the same general pattern: air has a tendency to move from cooler, high pressure areas to warmer, low pressure areas. The redistribution of energy by air masses is what keeps the low latitude areas from perpetually heating and the high latitudes from perpetually cooling.
|
|
|
Define and explain the coriolis force...
|
Wind has seeks to move from areas of high to low pressure. However, the earth's rotation has an effect on wind direction that deflects it to the right of its path in the northern hemisphere and to the left of its path in the southern hemisphere.
|
|
|
Explain how the coriolis force differs in intensity depending on the latitude and velocity of the moving object...
|
The amount of turning about a vertical axis varies from a maximum at the poles to a minimum at the equator. Therefore, the effect of the coriolis force increases with increasing distance from the equator. Also, the coriolis force increases in intensity as the air mass increases in velocity.
|
|
|
Define and explain geostrophic wind...
|
Geostrphic wind is the theoretical wind that would result from an exact balance between the coriolis force and the pressure gradient force, causing air to move parallel to isobars. This wind is only possible under conditions where isobars are perfectly straight and there is little or no friction, conditions rare in nature.
|
|
|
Define and explain gradient winds...
|
In the case where isobars have curvature, as around high or low pressure zones, it is not enough to consider only the coriolis force and the pressure gradient force. The centripetal force acting on a parcel of air as is rotates around a zone of high or low pressure must also be considered.
|
|
|
Describe the three cell model of global air circulation...
|
The hadley cell - 0-30 degrees
the ferrel cell - 30-60 degrees the polar cell - 60-90 degrees |
|
|
What is the ITCZ?
|
The equatorial region of the earth experiences a net gain of energy over the course of a year. The intense heat of this region is due to high sun angles and nearly equal day length throughout the year. The heat gained at these latitudes is transferred from the surface to the atmosphere by way of sensible heat transfer. The heated air gains bouyancy and easily rises through the tropical atmosphere. The convective rise of air promotes a broad area of low pressure that straddles the equator known as the ITCZ.
|
|
|
What is the subtropical high?
|
Air moving poleward from the ITCZ and air moving towards the equator from the sub-polar low meet between 25 and 35 degrees latitude, forming the subtropical high. The two air masses converge at the top of the troposphere and subside towards the surface. Subsidence towards the surface prevents the uplift of air, condensation, and precipitation. Thus, dry conditions prevail. The location of earth's major deserts, like the Sahara, coincides with the presence of the subtropical high.
|
|
|
What are the trade winds?
|
Equatorward of the subtropical high, the pressure gradient between 30 degrees latitude and the low over the equator creates the trade winds... in the NH, air is deflected to the right of its path creating the northeast trades while in the SE air is deflected to the left creating the southeast trades.
|
|
|
What are the westerlies?
|
On the poleward side of the subtropical high air heads poleward but is turned to create a westerly pattern between 30 and 60 degrees latitude, creating the westerlies.
|
|
|
What are the polar easterlies?
|
At the poles, high pressure air moves equatorward but is turned to create an easterly pattern between 90 and 60 degrees latitude.
|
|
|
What is the subpolar low?
|
The subpolar low is a zone of low pressure at 60 degrees latitude created by the meeting of the westerlies and the subpolar easterlies.
|
|
|
What is the polar high?
|
The overall loss of energy at the poles creates very cold air that subsides towards the surface. This creates a dome of high pressure called the polar high.
|
|
|
What is convective precipitation?
|
Precipitation typical of intertropical regions. Solar radiation is absorbed at the surface and is transferred to the atmosphere via sensible heat transfer. The warm air mass becomes bouyant and ascends vertically.
|
|
|
Whats is frontal precipitation?
|
When two air masses of differring characteristics meet, the warmer, more humid mass of air is lifted over the cooler, dryer mass, causing the release of latent energy and the condensation of water molecules.
|
|
|
What is orographic precipitation?
|
Precipitation that results from air moving over a topographic barrier, such as a mountain.
|
|
|
What are hurricanes?
|
Centers of extreme low pressure formed in warm, tropical, ocean waters (5 to 15 degrees latitude). Winds can reach up to 250 km/hr and their diameters vary between 150 and 500 km. In asia they are known as typhoons.
|
|
|
What are tornadoes?
|
Form when two air masses of very different characteristics meet. They occur especially in inland, continental areas. Speads reach up to 400km/hr, however diameters are small, never exceeding 500 m.
|
|
|
What is acid rain?
|
Acid rain is primarily caused by the combustion of
|
|
|
Acid rain is primarily caused by...
|
the combustion of fossil fuels from cars and factories.
|
|
|
Altura pluvial...
|
the volume of water precipitated per unit area of surface area. L/m2
|
|
|
Intensity of precipitation...
|
altura pluvial per unit time ex)mm/hr
|
|
|
The Thornwaite and Mather water balance...
|
Uses an accounting procedure to analyze the allocation of water among various components of the hydrologic system. Inputs include precipitation and monthly temperature. Outputs can include monthly potential and actual evapotranspiration, soil moisture storage, surplus, and runoff.
|
|
|
BHC Normal...
|
Expresses averages of P and ETP as a climatological indicator of water availability. The seasonal cycle of water availability over an average year. This information is important for agricultural planning.
|
|
|
BHC Sequencial...
|
P and ETP data of specific years or periods in a particular region. Characterizes the seasonal characteristics (the highs and lows) of the year in question in an effort to make important decisions regarding water availability.
|
|
|
What is the Southern Oscillation?
|
The reversing pattern or surface air pressures between the eastern and western tropical pacific.
|
|
|
What is the El Nino?
|
The El Nino makes up part of the SO... it is the abnormal warming of surface ocean waters in the tropical pacific.
|
|
|
What happens during a normal (non-El Nino) year?
|
Easterly winds blow sea surface waters from the S. American coast towards the Indonesian coast in the tropical pacific. This leads to a buildup of warmer, deeper waters in the western tropical pacific and an upwelling of cooler, shallower waters in the eastern pacific. Warmer surface waters in the western pacific tend to promote heavy precipitation and thinderstorms over indonesia, while cooler waters in the eastern pacific tend to promote a high pressure zone that inhibits convective uplift and therefore precipitation. That is why we find dense tropical forest in Indonesia and desert conditions in Peru.
|
|
|
What happens during an El Nino year?
|
The weakening of the trade winds cause a reversal of ocean currents from the western pacific towards the eastern pacific. Warm water develops off the coast of S. America while cooler waters develop off the coast of Indonesia. This promotes high pressure, dry conditions in the western pacific and low pressure warm conditions in the eastern pacific. Dry conditions in Indonesia lead to drought and forest fires, while wet conditions in Peru lead to serious flooding. Also this upsets air circulation at other parts of the globe leading to irregular air patterns.
|
