Module 8 (Air Pressure and Winds)

How is air pressure defined? How does it change as one goes upward in the atmosphere?

the force exerted by air, whether compressed or unconfined, on any surface it contacts. Air pressure decreases with height.

If an air column is warmed (the air as a building figure), what happens to its height? Why?

The buildings height increases because hot air rises.

1. If an air column is cooled, what happens to its height? Why?

It decreases or compresses because cold air molecules compact together and become more dense.

How can simply heating and/or cooling air columns produce a complete air circulation?

The horizontal difference in temperature creates horizontal difference in pressure.

What weather instrument is used to measure air pressure? How does the original (mercury) barometer work?

Barometer. The mercury barometer works by atm pressure pushing against the dish at the bottom and pushes the mercury up as with pressure rising

What are lines of constant pressure (on a surface weather map) called?

Contour lines

1. What four forces affect the horizontal movement of air?

Pressure gradient force

Coriolis force

centripetal force

friction

What is a pressure gradient force? How is its magnitude calculated?

PGF are the differences in horizontal air pressure. it is calculated by the magnitude gradient

What is the relationship between isobar spacing, pressure gradient force, and wind speed?

The closer the isobars, the steeper the gradient, the stronger the pressure gradient force. Means stronger winds.

What causes the Coriolis force to exist?

Earth’s rotation

How does the Coriolis force affect the movement of wind and/or objects in the Northern Hemisphere? How about in the Southern Hemisphere?

Northern hemisphere: right of intended path

Southern H: left

What three factors affect the amount of deflection that the Coriolis force produces?

rotation (speed of earth)

Latitude

Objects speed

Can the Coriolis force change wind speed? Why or why not?

It influences wind direction not speed

What is the centripetal force?

the imbalance between PGF and CF

Do winds on an upper-level map blow parallel to or across height contours? Why?

Blows parallel to the contour lines because of geostrophic winds, more balance between PGF and CF.

Do winds on a surface map blow parallel to or across isobars? Why?

Blows across isobars, less balance, more friction

How come wind speed usually increases as one travels higher above the surface?

Less friction in higher altitudes meanings faster winds

What direction does friction act, with respect to the wind direction?

30 degrees,

What is hydrostatic equilibrium/balance?

PGF is balanced by downward gravitational pull (G) which when they are equal it is hydrostatic balance

What is the difference between an onshore wind and offshore wind?

Day: onshore; land hot (L), blows from colder waters (H) to warmer land (L)

Night: land is cold which blows colder land air to warmer waters