Chapter 18: Air, Pressure and Wind

What general weather conditions are to be expected when the pressure tendency is rising? When the pressure tendency is falling?

When the pressure tendency is rising, weather is expected to be fair or good. When the pressure tendency is falling, stormy or bad weather is expected.

Which prevailing wind belts converge in the stormy region known as the polar front?

Westerlies and polar easterlies.

Referring to the idealized model of atmospheric circulation, in which belt of prevailing winds is most of the United States?

Westerlies.

Explain the seasonal change in winds associated with India. What term is applied to this seasonal wind shift?

As the land surface heats up in summer, it generates a thermal low pressure. Air from the relatively high-pressure region over the ocean blows into this thermal low. This is called the monsoon

Unlike winds aloft, which blow nearly. parallel to the isobars, surface winds generally cross the isobars. Explain what causes this difference

At the surface, friction affects wind and as a result alters its direction. The pressure gradient force and the Coriolis effect at the surface causes air to move across the isobars. Aloft, geostrophic winds lack friction with Earth's surface and can travel more quickly as the Coriolis effect balances the PGF

For a surface low-pressure center to exist for an extended period, what condition must exist aloft?

Divergence of air

Which pressure belt is associated with the equator?

Equatorial low.

Briefly describe how the Coriolis effect influences air movement.

In the Northern Hemisphere, the Coriolis effect causes the deflection of the path of a moving object, including moving air, to the right. In the Southern Hemisphere, this deflection is to the left. The effect is greater with increasing latitude.

List two advantages of the aneroid barometer.

It is small and portable, and it can be readily connected to a recording mechanism.

Describe air pressure in your own words.

It is the pressure exerted on Earth's surface due to the weight of the overlying air molecules

What force is responsible for generating wind?

Pressure gradient force

Prepare a diagram with isobars and wind arrows that shows the winds associated with surface cyclones and anticyclones in both the Northern and Southern Hemisphere.

See Figure 18.12 for Northern Hemisphere reference; the opposite will hold true for the Southern Hemisphere.

The trade winds diverge from which pressure belt?

Subtropical high.

Write a generalization relating the spacing of isobars to wind speed

The close together the isobars are, the faster the wind speed