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Flashcards in Weather module 1 continued Deck (56)
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1
Q

Define wind

A

The horizontal movement of the air

2
Q

What initiates the movement of air

A

The pressure difference in the horizontal causes air to move

3
Q

Define pressure gradient force

A

The force that starts the movement of air directly from a region of high pressure to a region of lower pressure.

4
Q

The effect of the earth’s rotation on wind’s direction is called: and what direction does it deflect it

A

The coriolis effect. to the right

5
Q

What is Buys-Ballot law?

A

if you stand with your back to the wind in the northern hemisphere the lower pressure will lie to your left.

6
Q

when a low or high pressure system passes to the north of your station the winds will:

A

veer

7
Q

wind speeds are ________ to the pressure gradient

A

directly proportional

8
Q

Define friction force

A

The force which results from the wind interacting with the earth’s surface

9
Q

Friction ______ wind speed and ______ wind direction. What does it do to the coriolis effect?

A

diminishes and modifies. It counteracts the coriolis effect.

10
Q

Is the greatest friction over land or sea?

A

land

11
Q

During ascent from sfc to 1000m wind will?

A

increase and veer

12
Q

During descent from 1000m to sfc wind will

A

decrease and back

13
Q

During daytime heating, wind will?

During nightime cooling, wind will?

A
  1. Veer and increase

2 back and decrease

14
Q

Define Gust

A

A relatively rapid increase in wind speed that lasts only briefly

15
Q

Define Squall

A

Wind speed increases suddenly and maintains a peak speed for several minutes before diminishing

16
Q

Sea breeze

A

A diurnal coastal breeze that blows onshore from the sea to the land

17
Q

Land breeze

A

a diurnal coastal breeze that blows offshore from the land to the sea

18
Q

Katabatic Winds

A

Winds that flow down ice free slopes at night or flows down ice covered slopes day and night.

19
Q

anabatic winds

A

Winds that blow up slopes during the day due to differential daytime heating

20
Q

Gusts are caused by what 2 ways?

A
  1. Mechanical turbulence

2. Unequal heating of the earth’s surface

21
Q

what are the 2 principal causes of squalls?

A
  1. Well developed Thunderstorms

2. fast moving cold fronts

22
Q

How are katabatic winds generated?

A

Sides of the valley are cooled by radiation at night and the air will flow down the slope.

23
Q

How are anabatic winds generated

A

the sides of a valley are heated during the daytime and the air rises. Cooler air from the bottom of the valley rushes up the sides to replace the rising air.

24
Q

What are the 3 topographical effects on air circulation

A
  1. Barrier effect
  2. Funnel effect
  3. Valley effect
25
Q

Define air mass

A

A large section of the troposphere that has relatively uniform temperature and moisture in the horizontal

26
Q

How are air masses formed?

A

An air mass is formed when a large section of air acquires the temperature and moisture characteristics of a vast area of the earth’s surface.

27
Q

What 2 terms are used to describe the moisture content of air masses?

A
  1. Continental

2. Maritime

28
Q

What 3 terms are used to describe the temperature of air masses in NA

A
  1. Arctic
  2. Polar
  3. Tropical
29
Q

Name the 4 air masses that occur over NA in winter

A
  1. Continental Arctic
  2. Maritime Arctic
  3. Maritime polar
  4. Maritime tropical
30
Q

what are the typical trajectories of the 4 airmasses

A

1 cA - southward
2 mA - South eastward and eastward
3. mP - Eastward and north eastward
4. mT - northerly

31
Q

describe the stability of each airmass

A
  1. Ca to mT Stable to unstable.
32
Q

with respect to stability, if the air is cooled from below, will it become more or less stable?

A

More stable

33
Q

What are the 6 factors that may change the temperature of airmasses?

A
  1. Changes in latitude
  2. change of season
  3. ocean currents
    4 movement from over water or over land
  4. Diurnal variations
  5. topography
34
Q

How would an air mass become destabilized?

A
  1. heating from below

2 cooling aloft (advection)

35
Q

how would an airmass become stabilized?

A
  1. By cooling from below (radiation cooling)

2. by heating aloft (advection)

36
Q

state the relationship between moisture content and air mass temperature

A

Warmer air masses can hold more water vapour than colder ones.

37
Q

what are 3 types of moisture increases and 1 type of moisture decrease in air masses?

A
  1. Movement over water
  2. Melting/evaporation of snow
  3. movement over regions of dense vegetation
    1b. Condensation/precipitation
38
Q

define front

A

the transition zone between 2 air masses

39
Q

name the 3 frontal systems located over Canada in the winter

A
  1. Continental Arctic
  2. Maritime Arctic
  3. Maritime Polar
40
Q

Define Frontal surface

A

The transition zone separating warm and cold air aloft

41
Q

Define Surface front

A

The transition zone separating warm and cold air touching the earth’s surface

42
Q

Define Cold front

A

A transition zone between warm air and advancing cold air. A cold front is always followed by cold air

43
Q

Define warm front

A

A transition zone between warm air and retreating cold air.

44
Q

Stationary front

A

A transition zone between two air masses that are not moving.

45
Q

The severity of the weather caused by a front depends on which factors (5)

A
  1. The slope of the frontal surface
  2. The speed of the front
  3. Temperature of the lifted air mass
  4. Moisture content of the lifted air mass
  5. Stability of the lifted air mass
46
Q

With respect to temperature, dew point temperature and pressure, what happens when a cold front or warm front passes

A

Cold front: Decrease in temperature (maybe a slight increase before the drop), decrease in dew point temperature and pressure rises.
Warm front: Increase in temperature, increase in dew point, a general fall in pressure as a warm front approaches.

47
Q

what are the average slopes of warm, cold and stationary fronts

A

Cold: 1:50
Warm 1:200
Stationary 1:100

48
Q

At a warm front, describe the 3 factors that determine cloud type and precipitation

A
  1. The moisture content of the overrunning air
  2. The stability of the overrunning air
  3. The degree of overrunning
49
Q

At a cold front, describe the 3 factors that determine cloud type and precipitation

A
  1. The moisture content of the lifted warm air
  2. The stability of the lifted warm air
  3. The degree of lift a. the slope of the frontal surface b. the speed of the front
50
Q

If warm air is moist and stable, expect the following clouds as the warm front approaches your station

A

1.CI,CS,AS,NS and continuous precipitiation.

51
Q

If the warm air is moist and unstable, expect the following clouds as the warm front approaches your station

A
  1. CI,CS,AS,NS and embedded CBs.continuous precipitation.
52
Q

As the cold front approaches, in moist and stable air what type of clouds will form when the front approaches rapidly and slowly

A

slowly: wide spread layer clouds and intermittent or continuous precipitation
Rapidly: Narrower band of clouds and continuous or intermittent precipitation

53
Q

Define frontal wave

A

A wave shaped distortion on a front usually associated with a trough

54
Q

what is frontogenesis and frontolysis?

A

Frontogenesis is the formation of a front

Frontolysis is the dissipation of a front.

55
Q

What is the area between a warm front and a cold front in a frontal wave called?

A

Warm sector

56
Q

What are the 3 main factors that determine cloud characteristics?

A
  1. Stability of the air
  2. moisture available in the air
  3. temperature of the air