Meteorology 1

Question 1

Standard Atmosphere

Answer 1

• Air is a perfectly dry gas
• MSL pressure of 29.92 inches of mercury
• MSL temperature of 15ºC
• Lapse rate of 1.98ºC/1000 ft

Question 2

Principle Properties of the Atmosphere

Answer 2

• Expansion
• Compression
• Mobility

Question 3

Sources of Moisture in Atmosphere

Answer 3

• Evaporation from oceans and lakes
• Transpiration from vegetation

Question 4

Heating Processes - Conduction

Answer 4

• Heating through contact
• Air is poor conductor so limited in effect

Question 5

Heating Processes - Convection

Answer 5

• Air that is warmed becomes less dense and tends to rise
• Rising continues until density (temp) is same as surrounding air

Question 6

Heating Processes - Turbulent Mixing

Answer 6

• Friction causes eddies to form as air moves over surfaces
• Disruption is proportionate to terrain (rough terrain = more mixing)
• Can rise high into troposphere when combined with convection

Question 7

Heating Processes - Advection

Answer 7

• Horizontal movement of air masses
• If it travels over a warm surface, the air mass will be warmed

Question 8

Heating Processes - Compression

Answer 8

• Descending (subsiding) air increases in pressure, in turn increasing temperature
• Can occur along ridges of high pressure or over mountain ranges
• Known as adiabatic heating

Question 9

Heating Processes - Release of Latent Heat

Answer 9

Changing state down an energy level releases heat energy and vice versa

Question 10

Cooling Processes - Expansion Cooling

Answer 10

• Rising air expands, which causes a decrease in temperature (adiabatic cooling)
• Dry or saturated adiabatic lapse rate

Question 11

Cooling Processes - Orographic and Upslope Lift

Answer 11

• Air flowing over topographical features causing it to rise
• Slope of terrain not important

Question 12

Cooling Processes - Frontal Lift

Answer 12

Expansion cooling when warm air is forced up along a frontal surface

Question 13

Cooling Processes - Mechanical Turbulence

Answer 13

Friction causes eddies to form as air moves over surfaces

Question 14

Cooling Processes - Convection

Answer 14

Rising air cools according to the appropriate lapse rate

Question 15

Cooling Processes - Convergence

Answer 15

Air at the centre of a low pressure area rises, causing cooling

Question 16

Inversions

Answer 16

Generally associated with a layer of haze with a very sharp top typically found 1000 ft AGL

Question 17

Factors Affecting Inversions

Answer 17

• Wind
• Cloud Affect
• Topographical Effect
• Maritime Effect

Question 18

Dew Point Lapse Rate

Answer 18

0.5ºC/1000 ft

Question 19

Vertical Development Clouds

Answer 19

• Bases range from 1000 ft or lower to 10,000 ft or higher
• Composed of water droplets or ice crystals
• Usually contain super-cooled water above the freezing level

Question 20

Requirements for Formation of Fog

Answer 20

• High Relative Humidity
• Abundance of Condensation Nuclei
• Mixing Action
• Fog dissipates as air temp rises

Question 21

Radiation Fog

Answer 21

Formed on cool clear nights with high relative humidity

Question 22

Advection Fog

Answer 22

• Formed in coastal areas when warm moist air moves over a cold land surface
• Does not burn off, requires a change in wind direction

Question 23

Steam Fog

Answer 23

• Formed when cool air moves over warm water surfaces
• Found over rivers and small lakes
• Evaporation occurs and saturates the air

Question 24

Ice Fog

Answer 24

• Forms on very cold days
• Consists of very small ice crystals
• Associated with hoar frost

Question 25

Difference between fog and mist

Answer 25

• Fog is less than 5/8 SM vis
• Mist is more than 5/8 SM vis