Chapter 5: Wind

Question 1

wind is

Answer 1

a horizontal movement of air

Question 2

Differences in temperature create

Answer 2

differences in pressure

Question 3

Wind is a horizontal movement of air. Differences in temperature
create differences in pressure. The pressure differences drive

Answer 3

a complex system of wind in a never ending attempt to reach equilibrium

Question 4

Wind is a horizontal movement of air. Differences in temperature create differences in pressure. The pressure differences drive a complex system of wind in a never ending attempt to reach equilibrium. So the wind is the result of

Answer 4

horizontal differences in air pressure

Question 5

The wind direction is measured by

Answer 5

the wind vane

Question 6

The wind direction is measured by the wind vane. This instrument,
which is a common sight on

Answer 6

many buildings, always points into the wind

Question 7

The wind direction is measured by the wind vane. This instrument,
which is a common sight on many buildings, always points into the wind,
sometimes the wind direction is shown on

Answer 7

a dial that is connected to the wind vane.

Question 8

The dial indicates

Answer 8

the direction of the wind either by points of the compass-that is, North (N), Northeast (NE), East (E), southeast (SE), and so on or by a scale of 0 to 360

Question 9

On latter scale.0 (or 360) is

Answer 9

north. 90 is east, 180 is south and 270 is west

Question 10

If the wind blows from the west the wind direction is

Answer 10

westerly

Question 11

If the wind blows from the west the wind direction is westerly, if it from the south east – its

Answer 11

south easterly and so on

Question 12

The wind speed units are:

Answer 12

meter per second m/s
kilometer per hour km/hour
knot; one knot = 0.51 m/s or = 1.9 km/hour.

Question 13

Factors affecting wind:

Answer 13

Force generating wind (pressure gradient force)

Coriolis force

Friction

Question 14

Pressure differences must create

Answer 14

a force in order to drive the wind this force is pressure gradient force.

Question 15

Pressure differences must create a force in order to drive the wind this force is pressure gradient force. The force is from

Answer 15

higher pressure to lower pressure and is perpendicular to the isobars or contours.

Question 16

The larger pressure differences ( ……………………….) the……………………. the …………………….

Answer 16

( the closer the spacing between the isobars) the stronger the pressure gradient force, the stronger is the Wind.

Question 17

The magnitude of the pressure gradient force is a function of

Answer 17

the pressure difference between two points and air density

Question 18

PGF
It can be expressed as:

Answer 18

-(1/p)(Δp/Δx)

Question 19

All free moving objects including wind are deflected to

Answer 19

the right of their path of motion in the Northern Hemisphere and to the left in the Southern Hemisphere.

Question 20

All free moving objects including wind are deflected to the right of
their path of motion in the Northern Hemisphere and to the left in the
Southern Hemisphere.
The reason of this deflection is

Answer 20

the earth’s rotation

Question 21

For example if a rocket moved from the North Pole toward a target on the
Equator and took one hour to arrive its target, then the earth will rotate

Answer 21

15^o in this time

Question 22

For example if a rocket moved from the North Pole toward a target on the
Equator and took one hour to arrive its target, then the earth will rotate 15 in this time. So the rocket would look as it

Answer 22

veers off its path and hit the ground 15^o west of the target

Question 23

Coriolis force

Answer 23

deflects the free moving objects to the right in the Northern Hemisphere because of its counter clockwise rotation, and to the left in the southern Hemisphere because of the clockwise rotation of the earth in the Southern Hemisphere

Question 24

The mathematical formula of computing the Coriolis force is :

Answer 24

Fc= 2ων sinθ

Question 25

Where Fc is

Answer 25

the Coriolis force measured in m/s²

Question 26

ω Is

Answer 26

the angular rotation of the earth (which is equal 7.29x10^-5 rad/s

Question 27

The main properties of the Coriolis force are:

Answer 27

- Fc is directly proportional the latitude and wind speed. - It deflects the free-moving object to the right in the N.H. and to the left in the S.H. - It affects the wind direction only not affects the wind speed.

Question 28

Friction

Answer 28

acts to slow a moving objects and to change the direction. Its direction is always opposite to the direction of the wind.

Question 29

Friction as a factor affecting wind is important only within

Answer 29

the first few kilometers of the atmosphere

Question 30

The roughness of the of the terrain determines

Answer 30

the angle at which the air flow will cross the isobar as will as influencing the speed at which it will move

Question 31

Where the friction is low (over smooth ocean surface), air moves at an angle of

Answer 31

10 to 20 degrees with the isobar and at speeds roughly two-third of the geostroghic wind.

Question 32

The geostroghic wind is

Answer 32

the resultant wind of the balance between the pressure gradient force and the Coriolis force on the free atmosphere.

Question 33

On the free atmosphere the effect of the friction force is

Answer 33

negligible.

Question 34

Over the rigged terrain the angle between the wind direction and the isobar is

Answer 34

high (may reach 30-45 degrees) and the wind speed is reduced by much as 50 % of the geostroghic wind.

Question 35

As said earlier, friction significantly influences

Answer 35

airflow near the earths surface and negligible at a height of few kilometers above

Question 36

Aloft where is no friction the Coriolis force

Answer 36

balances the pressure gradient force and deflects the wind direction to the right at an angle of 90 in the Northern Hemisphere to move in a direction parallel to the contours

Question 37

Contours are

Answer 37

the lines of equal heights. This wind is called geostroghic wind

Question 38

gradient wind:

Answer 38

this is assumption to calculate wind in uniform circular systems such as tropical cyclones.

Question 39

object moving around a circle needs

Answer 39

a force that is overcoming the desire of the object to move at a straight line. the force is called centripital force.

Question 40

define gradient wind

Answer 40

the wind which is a result of the balance of forces that are forcing the air to move in a uniform circle. those two forces are pressure gradient and corriolis

Question 41

thermal wind is

Answer 41

the change in the amplitude or sign of the geostrophic wind due to a horizontal temperature gradient. it is the difference between the upper and lower geostrophic wind.

Question 42

thermal wind is used to indicate

Answer 42

the thermal advection in a baroclinic atmosphere

Question 43

thermal wind is parallel to

Answer 43

the thickness

Question 44

the cold air (lower thickness) is to .............................

Answer 44

the left of the thermal wind

Question 45

cold advection:

Answer 45

thermal wind causes the geostrophic wind to rotate counterclockwise with heigh (backing)

Question 46

warm advection

Answer 46

thermal wind causes the geostrophic wind to rotate clockwise with heigh (veering)

Question 47

ageostrophic wind

Answer 47

the difference between actual and geostrophic winds

Question 48

ageostrophic wind is used to

Answer 48

include the effect of divergence in the upper air

Question 49

ageostrophic wind is measured by

Answer 49

soundings (radiosondes) and geostrophoc

Question 50

the ageostrophic wind is the value that is causing

Answer 50

the vertical motion

Question 51

despite the fact that the midlatitude atmosphere is predominantly in

Answer 51

geostrophic balance

Question 52

despite the fact that the midlatitude atmosphere is predominantly in geostrophic balance, all weatehr occuring there is a result of

Answer 52

this small porion of wind(the ageostrophic) so it is responsible for the distribution of cyclones, anticyclonic, clouds and precipitation in the atmosphere

Question 53

the ageostrophic wind is used to measure the horizontal acceleration in the

Answer 53

curvature and jets. it is normal to them and directed to the left.

Question 54

Jet streams:

Answer 54

Wind in the average increases with height throughout the troposphere cumulating in a maximum near the level of the tropopause.

Question 55

Jet streams: Wind in the average increases with height throughout the troposphere cumulating in a maximum near the level of the tropopause. This maximum winds tend to be

Answer 55

further concentrated in a narrow bands

Question 56

Jet streams: Wind in the average increases with height throughout the troposphere cumulating in a maximum near the level of the tropopause. This maximum winds tend to be further concentrated in a narrow bands. These narrow bands of strong winds meandering through the atmosphere at a

Answer 56

level near the tropopause

Question 57

Types of jet streams

Answer 57

polar jet stream which is concentrated in midlatitude between 40^o and 60^o. - subtropical jet stream at 30^o latitude.

Question 58

Main characteristics of the jet streams:

Answer 58

* jet streams typically occur in the break of the tropopause. * - the form in area of intensified temperature gradients. * - the wind speed must be 50 knots or greater to cla ssify as a jet stream. * - the jet stream maximum is not constant rather its broken into segments. * - the polar jet shifts farther south and it is stronger in winter than in summer. * - jet stream segments move with the pressure ridges and troughs in the upper atmosphere.

Question 59

Local terrain features such as mountains and shore lines influence

Answer 59

local winds and weather.

Question 60

Mountain and Valley wind:

Answer 60

In the daytime air next to a mountain slope is heated by the contact with the ground as it receives radiation from the sun. The air usually becomes than air at the same altitude but farther from the slope. Colder denser air in the surroundings settles downward and forces the warmer air near the ground up the slope. This wind is a Valley wind, so called because the air is flowing up out of the valley. At night the air in contact with the mountain slope is cooled by terrestrial radiation and becomes heavier than the surrounding air. It sinks on the slope producing the Mountain wind which flows l ike water down the mountain slope Mountain winds are usually stronger than valley winds, especially in winter.

Question 61

Land and Sea breezes:

Answer 61

As we know land surfaces warm and cool more rapidly than do water surfaces, therefore land is warmer than the sea during the day. So wind blows from cool water to warm land.

Question 62

The sea breeze so called because

Answer 62

it blows from the sea. At night the wind reverses, blows from cool land to warmer and creates the “land breeze”. Land and sea breeze develop only when the overall pressure gradient is weak. Wind with stronger pressure gradient mixes the air so rapidly that local temperature and pressure gradient do not develop along the shore line.

Question 63

the speed units

Answer 63

knot, meter per second, kilometer per hour and feet per second which they are related by: 1 kt= 0.515 m/s = 1.853 km/h =1.152 mi/h = 1.689ft/s

Question 64

wind speed may be indicated in

Answer 64

makes use of familiar, natural phenomena connected with different wind speeds.

Question 65

An anemometer is a device for measuring

Answer 65

wind speed and direction

Question 66

An anemometer is a device for measuring wind speed and direction. The term is derived from the Greek word anemos, meaning

Answer 66

wind

Question 67

An anemometer is a device for measuring wind speed and direction. The term is derived from the Greek word anemos, meaning wind. It is divided into:

Answer 67

Wind Vane. Wind vane measures the wind direction. - A cup anemometer. The cup anemometer measures the wind speed. The wind speed is read from a dial much like the speedometer of an automobile.

Question 68

Wind sock consists of

Answer 68

a cone shaped bag that is open at both ends. The degree to which the sock is inflated is an indication of the strength of the wind.