Lecture 8 Air Pressure and Global Wind

Question 1

The molecules that constitute air create ______.

Answer 1

air pressure

Question 2

True or False: Therefore, warmer air is less dense, or lighter, than colder air, and exerts less pressure.

Answer 2

TRue

Question 3

True or False: Moist air is lighter because the molecular weight of water is less than that of the molecules making up dry air.

Answer 3

True

Question 4

humid air is associated with ______ pressure and cold, dry air is associated with ______ pressure.

Answer 4

low, high

Question 5

Any instrument that measures air pressure is a ______.

Answer 5

barometer

Question 6

______ is generally the horizontal motion of air across Earth’s surface.

Answer 6

wind

Question 7

An ______ measures wind speed in kilometres per hour

Answer 7

anemometer

Question 8

What are the four forces that determine both speed and direction of winds?

Answer 8

gravitational force
pressure gradient force
Coriolis force
Centrifugal force

Question 9

The _______force counteracts the outward ______ force acting on Earth’s spinning surface and atmosphere.

Answer 9

gravitational, centrifugal

Question 10

______ drives air from areas of higher barometric pressure (more-dense air) to areas of lower barometric pressure (less-dense air), thereby causing winds

Answer 10

pressure gradient force

Question 11

True or False: cold, dry, dense air at the poles exerts greater pressure than warm, humid, less-dense air along the equator.

Answer 11

True

Question 12

An ______ is an isoline plotted on a weather map to connect points of equal pressure

Answer 12

isobar

Question 13

The ______ is a deflective force that makes wind travelling in a straight path appear to be deflected in relation to Earth’s rotating surface

Answer 13

coriolis force

Question 14

Because Earth rotates eastward, such objects appear to curve to the ______ in the Northern Hemisphere and to the ______ in the Southern Hemisphere.

Answer 14

right, left

Question 15

In the boundary layer, ______ drags on the wind as it moves across Earth’s surfaces but decreases with height above the surface.

Answer 15

friction force

Question 16

Pressure gradient + coriolis forces move air from _______ (anticyclone) to ______ (cyclone) from high to low pressure in Northern hemisphere and move air from _______ (anticyclone) to ______ (cyclone) from high to low pressure in Southern hemisphere

Answer 16

clockwise, counter clockwise

counter clockwise, clockwise

Question 17

winds that do not flow directly from high to low but flow around the pressure areas, remaining parallel to the isobars are ______

Answer 17

geostrophic winds

Question 18

surface winds spiralling clockwise out of the high-pressure area toward the low pressure are _______, where winds spiral counterclockwise into the low _______

Answer 18

Diverging, and converging

Question 19

When geostrophic winds approach the surface, they are slowed by friction and are called ______.

Answer 19

surface winds

Question 20

True or False: Surface winds cross isobars at oblique angles due to the increase in frictional force near
the surface.

Answer 20

True

Question 21

True or False: Surface winds are influenced by surface roughness

Answer 21

True

Question 22

WHat are the 4 pressure belts

Answer 22

Polar high
Thermal 90° N, 90° S Cold/dry

Subpolar low
Dynamic 60° N, 60° S Cool/wet

Subtropical high
Dynamic 20°–35° N, 20°–35° S
Hot/dry

Equatorial low
Thermal 10° N to 10° S Warm/wet

Question 23

The winds converging at the equatorial low are known generally as the ______.

Answer 23

Trade winds

Question 24

The ______ diminish somewhat in summer and are stronger in winter in both hemispheres.

Answer 24

westerlies

Question 25

They descend and diverge clockwise in the Northern Hemisphere (counterclockwise in the Southern Hemisphere) and form weak, variable winds of the polar ______.

Answer 25

easterlies

Question 26

Surface air diverging within the subtropical high-pressure cells generates Earth’s principal surface winds: the trade winds that flow toward the equator, and the ______.

Answer 26

Westerlies

Question 27

Consider a thick column of air in the atmosphere, if that air cools:

Answer 27

• it contracts
• its density increases
• and the local air pressure increases

Question 28

if the air warms:

Answer 28

• it expands
• its density decreases
• and the local air pressure falls