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Ground School > Weather > Flashcards

Weather Flashcards

1
Q

What is the atmosphere

A

The envelop of air that surround earth

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2
Q

By weight, how much of the atmosphere is located below 18,000?

A

1/2

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3
Q

What is the movement of air around the surface called

A

atmospheric circulation

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4
Q

What gas accounts for 78% of the gas in our atmosphere?

A

Nitrogen

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5
Q

What affects pressure changes

A

Altitude, temperature, density of air.

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6
Q

Pressure charts use what pressure indication?

A

milibars

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7
Q

what is the acronym for milibars

A

(mb)

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8
Q

What are local barometric pressure readings converted to?

A

sea level pressure

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9
Q

What are isobars

A

pressure area outlines

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10
Q

On a pressure chart how far apart are isobars placed

A

4 mb apart, unless significant pressure gradient then 2 mb apart

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11
Q

What does rising pressure indicate

A

Approach of fair weather

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12
Q

What does falling pressure usually indicate?

A

approaching of bad weather

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13
Q

What is temperature

A

Measurement of amount of heat, expresses a degree of molecular activity

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14
Q

what is incoming solation heat called

A

insolation

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15
Q

what is radiating heat from earths surface called?

A

Terrestrial radiation

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16
Q

On the Fahrenheit scale what is freezing

A

32 degrees

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17
Q

on the Fahrenheit scale what is boiling

A

212 degrees

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18
Q

on the Celsius scale what is freezing

A

0 degrees

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19
Q

on the Celsius scale what is boiling

A

100 degrees

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20
Q

how do you convert Fahrenheit to Celsius

A

subtract 30 and then divide by 2

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21
Q

how do you convert Celsius to Fahrenheit

A

multiply by 2 add 30

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22
Q

what causes atmospheric circulation

A

temperature variations

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23
Q

What is Diurnal Variation

A

Change of temperature from day to night

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24
Q

when does terrestrial radiation cease?

A

After sunrise when insolation overtakes terrestrial radiation

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25
Q

Does water absorb or radiate heat quickly or slowly

A

quickly

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26
Q

where does abrupt temperature changes occur?

A

along water shorelines

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27
Q

where prevailing winds come from a large body of water what happens to temperature changes

A

slow temperature changes with small gradient

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28
Q

where prevailing winds come from dry barren areas what happens to temperature changes

A

quick temperature changes with large gradient

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29
Q

What happens to temperature with increasing altitude?

A

Temperature typically decreases

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30
Q

What is a lapse rate

A

the decrease of temperature with increase of altitude

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31
Q

What is an inversion

A

a layer of warmer air over a layer of colder air

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32
Q

What is conduction

A

the transfer of heat energy from one substance to another

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33
Q

what is convection

A

The transfer of heat in a fluid

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34
Q

where does conduction occur

A

a few centimeters off of the surface

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35
Q

when does convection ocur

A

as the ground is heated by the sun.

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36
Q

When do inversions develop

A

cool clear nights with light and variable winds

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37
Q

Why do inversions occur

A

Grounds air cools faster than moist air above

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38
Q

Whey do low level inversions dissipate

A

as air is heated with insolation the inverted air begins to mix due to convections

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39
Q

List 3 ways heat is transferred to the atmosphere

A

Radiation, Conduction, convection

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40
Q

What is radiation

A

transfer of heat by electromagnetic waves

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41
Q

Is there a medium needed for heat transfer in radiation

A

no

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42
Q

What are principle reflectors in meterology

A

water vapor, particulate matter and the earths surface

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43
Q

what is advenction

A

the horizontal transfer of heat, usually by wind

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44
Q

what is the adiabatic process

A

change of temperature without the transfer of heat

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45
Q

in the adiabiatic process what results in warming

A

compression

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46
Q

in the adiabiatic process what results in cooling

A

expansion

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47
Q

What happens to air as it rises

A

pressure decreases, volume increases, temperature decreases

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48
Q

what happens to air as it descends

A

pressure increases, volume decreases and temperature increases

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49
Q

what are the basic characteristics of any air mass

A

temperature and humidity

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50
Q

what is the primary factor in determining air mass characteristics

A

terrain

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51
Q

what is an air mass

A

a large body of air that has uniform characteristics

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52
Q

What are characteristics of an air mass

A

Stability, cloud type, sky coverage, visibility precipitation, icing, turbulence

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53
Q

how are air masses grouped

A

by region of origination

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54
Q

what types of airmasses are there

A

polar or tropical and maritime or continental

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55
Q

what happens to air masses as they move over a warm surface

A

the air is heated from below and becomes unstable

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56
Q

what happens to air masses as they pass over a cold surface

A

air is cooled from below creating a stable air mass with poor visibility

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57
Q

why is poor visibility a characteristic of stable air

A

Particles are trapped and cant rise

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58
Q

what local weather can be found with cold, stable air

A

low stratus clouds and fog

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59
Q

what does moist unstable air cause

A

Cumulus clouds, good visibility , localized showers and turbulence

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60
Q

The heating and cooling of air can cause what in density

A

it can cause density variations

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61
Q

what happens to a barometer in a low pressure

A

pressure decreases towards the center

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62
Q

which way does the wind spin in a low

A

counter clockwise

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63
Q

What are the flying conditions noted with a low pressure system

A

poor flying conditions, low clouds, restricted visibility (fog and precipitation) strong gusty winds, turbulences

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64
Q

what happens to air if it passes over a colder surface

A

creates a stable air mass with poor visibiltiy

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65
Q

Why is poor visibility a characteristic of stable air

A

particles are trapped and cant rise

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66
Q

what local weather can be found with cold stable air

A

low stratus clouds and fog

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67
Q

What happens to air as it is heated from below

A

it becomes unstable

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68
Q

what can unstable air cause

A

cumulus clouds, good visibility localized showers and turbulence

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69
Q

What are flying conditions of a low

A

low clouds, restricted visibility (fog and precipitation) strong gusty winds, turbulences

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70
Q

what is the general airflow of a low pressure?

A

towards the center and up

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71
Q

what is a high pressure system

A

barometric pressure increases towards the center

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72
Q

heating and cooling of the air can do what to density

A

it can cause density variations

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73
Q

what happens to pressure in a low

A

barometric pressure decreases towards the centre

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74
Q

which way does the wind spin in a low

A

counterclockwise

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75
Q

what is advection

A

the horizontal transfer of heat

76
Q

what is the adiabatic process

A

the change of temperature without the thansfer of heat

77
Q

In the adiabiatic process what results in warming

A

compression

78
Q

in the adiabiatic process what results in cooling

A

expansion

79
Q

what is conductions

A

transfer of heat energy from one substance to another

80
Q

where does conduction occur

A

a few centimeters off the surface

81
Q

what is convection

A

the transfer of heat in a fluid

82
Q

when does convection occur

A

when the ground is heated by the sun (insolation)

83
Q

what is raiation

A

the transfer of heat by electromagnetic waves

84
Q

is there a medium needed for heat transfer in radiation

A

no

85
Q

what are principle reflectors in meterology

A

water vapor, particulates, earths surface

86
Q

where do abrupt temperature changes occur

A

along water shorelines

87
Q

what is the general pattern of air flow in a high pressure system

A

clockwise

88
Q

what are flying conditions of a high pressure system

A

few clouds, light and calm winds less turbulence

89
Q

what type of front moves most rapidly

A

cold fronts

90
Q

how fast do cold fronts move

A

about 25-30 miles per hour

91
Q

what weather pattern could you see with a cold front

A

rain showers, haze, wind from the S.W. high dew point and falling barometric pressure

92
Q

how is visibility in a cold front

A

poor

93
Q

what types of clouds are present in a cold front

A

cirriform, cumulus and cumulonimbus

94
Q

what winds can be seen in a cold front

A

light and variable

95
Q

when is the movement of pressure systems more rapid?

A

winter

96
Q

what is a front

A

it is the boundary between two masses

97
Q

how are fronts classified

A

which type of air mass is replacing another

98
Q

what are fronts boundaries for

A

two air masses with different densities

99
Q

what is primary control in air density

A

temperature

100
Q

what types of fronts are there

A

Cold, Warm Stationary and occulded

101
Q

how are fronts determined

A

movement of air masses involved

102
Q

what is a cold front

A

advancing edge of a cold air mass

103
Q

when does a cold front occur

A

a mass of cold dense air replaces a body of warmer air

104
Q

what is a warm front

A

trailing edge of a cold air mass

105
Q

how fast to warm fronts move

A

10-15 mph

106
Q

what causes the wind to move

A

the corilois force, pressure gradient and surface friction

107
Q

what is atmospheric circulation

A

movement of air around the surface of the earth caused by uneven heating

108
Q

in general atmospheric theory states ow pressure exists over what region

A

equatorial

109
Q

In general atmospheric pressure theory states high pressure exists over what region

A

polar regions

110
Q

where is the greatest amount of air deflection noted

A

around the poles

111
Q

Coriolis force deflection is perpendicular to what

A

airflow

112
Q

which direction in Northern Hemisphere does air get deflected

A

to the right

113
Q

what are pressure gradients

A

difference in pressure between high and low

114
Q

wind speed is directly proportional to

A

pressure gradient

115
Q

what are the three components that affect wind

A

Coriolis, pressure gradients, surface friction

116
Q

what is the humidity like in a high pressure system

A

dry

117
Q

is the air in a high pressure system stable or unstable

A

stable

118
Q

does the air descend or ascend in a high pressure

A

descend

119
Q

Is air in a low stable or unstable

A

unstable

120
Q

what weather is associated with a low

A

increase in cloudiness and precipitaitaion

121
Q

what is anabatic wind

A

winds that blow up a steep mountain side

122
Q

when do anabatic winds occur

A

day time, calm sunny weather

123
Q

what is a katabatic wind

A

winds flowing down slope

124
Q

when do katabatic winds occur

A

at night

125
Q

how are cloud types determined

A

height, shape and behavior

126
Q

how are clouds classified

A

height at bases

127
Q

what are the 4 major cloud types

A

low, middle, high, and clouds with vertical development

128
Q

what are specific cloud types

A

cumulous, stratus, cirrus, castellans, lenticularis, nimbus, fracto and alto

129
Q

what are outward appearance of cumulous clouds

A

heaped towering clouds, piles

130
Q

what are the outward appearance of stratus clouds

A

formed in layers

131
Q

what are the outward appearance of cirrus clouds

A

ringlets, fibrous clouds at high level

132
Q

what are the outward appearance of Casellanus clouds

A

common base with separate vertical development

133
Q

What are the outward appearances of lenticular clouds

A

lens shaped over mountains, indicate strong winds

134
Q

What are nimbus clouds

A

rain bearing clouds

135
Q

what are fracto clouds

A

ragged or broken

136
Q

what are alto clouds

A

high elevation clouds

137
Q

where do low level clouds form

A

near earths surface

138
Q

what cloud groups make up low level clounds

A

stratus and stratcumulous

139
Q

Where do strato clouds form

A

near the surface

140
Q

what flying conditions do strato clouds form

A

poor visibility flying conditions

141
Q

where can mid level clouds form

A

6500 to 20k agl

142
Q

What cloud groups make up mid level clouds

A

Altocumulus, alto stratus, nimbostratus

143
Q

what are high clouds

A

clouds that form above 20k feet AGL

144
Q

where do high clouds form

A

above 20k in stable air

145
Q

what are high cloud groups

A

cirrus, cirruscumulus, cirrostratus

146
Q

what are cumulous clouds known for

A

extensive vertical development

147
Q

what do clouds with extensive vertical development develop into

A

thunderstorms

148
Q

what do towering cumulous clouds indicate

A

instability and turbulance

149
Q

flight in cumuliform can be

A

turbulent in and around cloud masses

150
Q

flight in stratoform clouds can be

A

smooth

151
Q

nimbus means

A

rain or precipitation producing clouds

152
Q

what is dew point

A

point where air can hold no more moisture

153
Q

at what rate does unsaturated air cool?

A

5.4 degrees f per 1,000

154
Q

what happens to dew point as altitude increases

A

dew point decreases 1 degree f per 1,000 feet

155
Q

what is convergence of temp and dew point

A

4.4 degrees

156
Q

What is the formula for determining cloud bases

A

temperature-dew point = temperature dew point spread, temperature dew point spread is divided by convergence rate multiplied by base of clouds gives elevation AGL
Temp-D.P=TDS
TDS/CR*1000=base of clouds

157
Q

what is fog

A

clouds that begin within 50 feet of surface

158
Q

what are natural conditions for fog to occur

A

relative high humiditiy

159
Q

what wind condition is favorable for fog

A

light wind causing mixing of cooled air

160
Q

What is radiation fog

A

when heat in the air is given back to atmosphere causing cooling and ambient air reaching dew point

161
Q

when is radiation fog most likely

A

Clear Skies, High moisture content, and wind less than 7 knots

162
Q

What does an unstable air mass allow

A

upward and downward movement of air

163
Q

what happens to rising air

A

expands and cools

164
Q

what does moisture do to air densitiy

A

decreases air density

165
Q

what air mass is more stable moist or dry

A

Dry air masses are more stable

166
Q

Cool Dry air is very

A

stable

167
Q

Cool Dry air resists

A

vertical movement

168
Q

what type of air mass does the greatest instability occur

A

moist warm air.

169
Q

what does air stability depend on?

A

vertical distribution of airs weight

170
Q

what are types of air stability

A 
Absolute stability
Absolute instability
conditional stability
neutral stability
convective stability
171
Q

when does absolute stability occur

A

when actual lapse rate is less than adiabatic lapse rates

172
Q

when does absolute instability occur

A

when the actual lapse rate is greater than the dry adiabatic process

173
Q

list the 4 categories of turbulance

A

thermal
mechanical
frontal
wind shear

174
Q

what is a thermal

A

updraft in a small scale convective current

175
Q

what is Mechanical turbulance

A

when air flows over irregular surfaces

176
Q

What does Mechanical turbulence depend on

A

speed of wind,
nature of obstruction
stability of air
angle at which air moves over obstacle

177
Q

what is frontal turbulance

A

lifting of warm air by frontal surface

178
Q

what is the most severe frontal turbulence associated with

A

Fast moving cold fronts

179
Q

What is a wind Shear

A

a steep grade of wind velocity

180
Q

what are low level wind shears associated with

A

passing frontal storms, thunderstorms and temperature inversions

181
Q

how many convective cells does a mature thunderstorm have

A

one or more

182
Q

How many stages are in a thunderstorm

A

3 stages

183
Q

What are the three stages of a thunderstorm

A

Cumulous, Mature, dissipating

184
Q

what is the chief distinguishing feature of the cumulous stage

A

up drafts

185
Q

What initiates the mature stage of a thunderstorm

A

surface rain, and adjacent updrafts and down drafts

186
Q

what happens to pressure in a thunderstorm

A

abrupt fall in pressure as storm approaches

abrupt rise in pressure as with rain as storm moves on

187
Q

what are frontal thunderstorms caused by

A

lifting of warm moist conditionally unstable air

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