Chapter 6

Question 1

Wind

Answer 1

air in motion that arises from a combination of forces

Question 2

Wind speed is reported on U.S. weather maps in ____________

Answer 2

knots

Question 3

Knots

Answer 3

One nautical mile per hour (equivalent to about 1.15 miles per hour, or 0.5 meters per second

Question 4

If the wind speed is strong (greater than 15 knots) and highly variable, the weather report will include the __________

Answer 4

wind gust - the maximum observed wind speed

Question 5

Wind direction

Answer 5

The direction from which the wind is blowing

Question 6

Cyclones

Answer 6

Low-pressure centers

Question 7

anticyclones

Answer 7

high-pressure systems

Question 8

velocity

Answer 8

the magnitude and direction of its motion

Question 9

speed

Answer 9

the distance traveled in a given amount of time

Question 10

acceleration

Answer 10

a change in an object’s velocity - magnitude, direction, or both

Question 11

Forces are characterized by:

Answer 11

direction and magnitude (or strength)

Question 12

Net force or Resultant

Answer 12

The overall force that results from interacting forces can be expressed as a single force

Question 13

Newton’s Second Law of Motion

Answer 13

A force exerted on an object (or a parcel of air) of a given mass causes the object to accelerate in the direction of the applied force

Question 14

Force =

Answer 14

Mass x Acceleration

Question 15

Acceleration =

Answer 15

Force / mass

Question 16

5 different forces combine to move air:

Answer 16

the gravitational force, the pressure gradient force (PGF), the centrifugal force, the Coriolis force, and the frictional force

Question 17

Gravitational force (GF)

Answer 17

Directed downward perpendicular to the ground and is approximately equal to the mass times the gravitational acceleration, 9.8 meters per second per second

Question 18

pressure gradient

Answer 18

A change in presure over a distance

Question 19

PGF always pushes from

Answer 19

higher pressure toward lower pressure

Question 20

PGF =

Answer 20

(- 1 / Air density) x (change in pressure / distance)

Question 21

When pressure changes rapidly over a small distance =>

Answer 21

PGF is large

Question 22

The PGF always pushes directly from

Answer 22

higher pressure toward lower pressure

Question 23

Isobaric maps are useful for portraying:

Answer 23

horizontal pressure gradients above the ground

Question 24

The steeper the slope of the pressure surfaces =>

Answer 24

the greater the PGF because the pressure gradient is the change in pressure over distance

Question 25

Centripetal acceleration

Answer 25

When an object changes its direction of motion, it is accelerating even if its speed does not change

Question 26

CENTF =

Answer 26

V^2 / R

V = wind speed

R = radius of curvature of the curved path

Question 27

The faster the speed and the tighter the curve of the path traveled (smaller R), the larger is the

Answer 27

centripetal acceleration

Question 28

Coriolis force

Answer 28

Characteried by a turning or deflection of the direction of moving air

Question 29

The Coriolis force deflects movement to +>

Answer 29

the right in the Northern Hemisphere

to the left in the Southern Hemisphere

Question 30

Frictional force is caused by:

Answer 30

The flow of wind over the roughness of the Earth’s surface

Question 31

What determine the magnitude of frictional force

Answer 31

The roughness of the surface and the speed of the wind

Question 32

Sum of Forces =

Answer 32

Mass x Acceleration

Question 33

When the vertical pressure gradient is equal to coriolis force (gravity) and push in opposite directions =>

Answer 33

hydrostatic balance exists

Question 34

When the PGF is counterbalanced by the Coriolis force =>

Answer 34

geostrophic balance

Question 35

Because the Coriolis force always pushes to the right of the wind in the Northern Hemisphere, this requries a wind in geostrophic balance =>

Answer 35

geostrophic wind

Question 36

Buys Ballot’s Law

Answer 36

The “low pressure lies to the left of the wind” rule

Question 37

Because air moves with low pressure on its left in the Northern Hemisphere =>

Answer 37

the wind must blow clockwise around highs and counterclockwise around lows

Question 38

Winds on a weather map are strong where:

Answer 38

isobars or isoheights are close together

Question 39

Winds on a weather map are weak where:

Answer 39

isobars or isoheights are far apart

Question 40

Gradient balance

Answer 40

The three-way balance of horizontal pressure gradient, Coriolis force, and centrifugal force

Question 41

The wind that results from gradient balance is called =>

Answer 41

gradient wind

Question 42

Supergeostrophic flow

Answer 42

The wind speed, to which the Coriolis force is proportional - must be considerably higher than in the purely geostrophic case

Question 43

For high and low pressure areas that have the same spacing of isobars or isoheights,, winds in gradient balance around a high will be:

Answer 43

stronger than winds around a low