3 Pressure and Atmospheric Circulation Free Online FlashCards

What is atmospheric pressure?

Atmospheric pressure is the force per unit area exerted by the weight of the air above a location.

Which force pushes air from high pressure toward low pressure?

The pressure-gradient force pushes air from higher pressure toward lower pressure.

How does the Coriolis effect deflect air in each hemisphere?

The Coriolis effect deflects moving air to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

What is the broad circulation pattern of a Hadley cell?

In the Hadley cell, air rises near the equator, moves poleward aloft, sinks in the subtropics near 30° latitude, and returns toward the equator near the surface.

How does a daytime sea breeze form?

During the day, land warms faster than water. Air over land rises, and cooler air flows inland from over the water as a sea breeze.

How does atmospheric pressure generally change with altitude?

Pressure generally decreases with altitude because less air lies above higher locations.

What do closely spaced isobars indicate about winds?

Closely spaced isobars indicate a steeper pressure gradient and, all else being equal, faster winds.

How does the Coriolis effect vary from equator to poles?

It is weakest at the equator and becomes stronger toward the poles.

Does the Coriolis effect start the wind?

It changes the direction of moving air but does not start the wind; pressure differences help drive wind.

How does friction change near-surface wind direction?

Above the surface, winds often flow roughly parallel to isobars. Near the ground, friction weakens the Coriolis effect, so wind crosses isobars toward lower pressure.

Which prevailing winds are associated with the Ferrel cell?

The Ferrel cell lies between about 30° and 60° latitude. Its average surface flow is poleward and deflected eastward, forming the prevailing westerlies.

How do polar easterlies form?

Near the surface, cold air flows from the poles toward lower latitudes and is deflected westward, producing polar easterlies.