Meteorology Exam Brief Questions Flashcards
Where can half of the water vapour in the atmosphere be found?
Below 6,500ft
What are the heights of the tropopause?
At the equator - approx. 60,000ft
At the poles - approx. 25,000ft
What is ISA?
International Standard Atmosphere
Dry air
Mean sea level temperature - 15°C
Mean sea level pressure - 1013.25 hPa
Lapse rate of 1.98°C per 1,000ft
Which part of the atmosphere is most important to aviation?
Troposphere
What is the change called from: water vapour to ice crystals?
Deposition
What is the change called from: water vapour to water droplets?
Condensation
What is the change called from: ice crystals to water vapour?
Sublimation
What is the change called from: liquid water to water vapour?
Evaporation
Name the 3 ways that heat is transferred through the atmosphere
Radiation
Conduction
Convection
What is the relationship between the temperature and the amount of water an air mass can hold?
The higher the temperature of an air mass the more water it can hold
What is the force that is generated by the rotation of the earth called?
The Coriolis Effect
What are the processes associated with latent heat?
Latent heat released:
- condensation
- deposition
- freezing
Latent heat absorbed
- evaporation
- melting
- sublimation
Define saturation
An air mass is saturated when it contains the maximum amount of water that it can hold at a given temperature
Define dew point
The temperature at which the air would become saturated
Define relative humidity
The ration between the actual water content of the air and amount of water vapour which could be held in the air mass at that temperature expressed as a percentage
Name the two processes by which precipitation is formed
Coalescence and deposition
What are the dry and saturated adiabatic lapse rates?
DALR - 3.0°C per 1,000ft
SALR - 1.5°C per 1,000ft
What does the Coriolis Effect affect in the northern and southern hemispheres?
The Coriolis Effect influences the direction of wind flow.
Southern hemisphere - wind turns to the left
Northern hemisphere - wind turns to the right
This accounts for the direction of wind around high pressure systems
What is an isobar?
A line of equal pressure
What are the main types of inversions?
Radiation
Turbulence
Subsidence
Frontal
What are the forces which affect wind strength and direction?
Pressure gradient
Friction
Coriolis Effect
Where is friction the greatest influence on wind?
Over land, close to the ground
What conditions must exist for frost or dew to form overnight?
Clear skies
Low temperatures
Light winds
For frost - temperatures below 0°C
What is an air mass?
An air mass is a large body of air with generally uniform temperature and pressure
They form in their source regions (areas where they pick up the properties of the surface)
What are a sea breeze and a land breeze?
Sea breeze - develop by day as the land warms faster than the sea and thus rises creating a breeze from the sea towards the land
Land breeze - the opposite; develop at later hours (and overnight) when the land cools much faster than the sea and thus the air sinks and creates a breeze toward the sea
What turbulence is commonly associated with Jet Streams?
Clear air turbulence
What lifting agents cause clouds to form?
Frontal Lifting
Orographic lifting
Turbulence
Convection
At the passage of a cold front, what would you expect to observe with respect to temperature, visibility, pressure and wind?
Vis - poor
QNH - arrest or fall
Temperature - Decrease
Wind - Sudden backing at a steady strength
List a number of weather events that would influence visibility
Rain Fog Mist Smoke Haze Dust Ash Snow Sand
What is the difference between mist and fog?
Fog is reported when visibility is less than 1000m
Mist is reported when visibility is between 1000m and 5000m
What are the ideal conditions for radiation fog?
Clear night
Moist air
Light wind
Long night
Name the different types of turbulence
Clear air turbulence Mechanical Thermal Frontal Wind shear Wake
What are the 3 requirements for the formation of a thunderstorm?
Unstable air
Moisture
Lifting agent (trigger)
What are the different types of icing?
Clear ice
Rime ice
Freezing rain
Snow and ice crystals
What are the stages of a thunderstorm?
Towering cumulus
Mature
Dissipation
What are the types of clouds and their stratum?
Low - Surface
SFC - 6,500ft
Middle - Alto
6,500ft - 20,000
High - Cirrus
20,000ft and above
What would a pilot encounter in stable conditions?
Low vis Steady precipitation Stratiform clouds Steady winds Smooth flying conditions
What would a pilot encounter in unstable conditions?
Good vis Showers of precipitation Cumuliform clouds Gusty winds Turbulence
Difference between forecast and observed
A forecast is a scientific estimate of the future weather conditions whereas observed weather is reported at a given time based on the current weather
