Meteorology Quiz & Test Flashcards
What is the composition of our atmosphere?
78% Nitrogen, 21% Oxygen, water vapour 0 to 3%, carbon dioxide 0.03%.
What commences a change of state in a substance (i.e. water)?
When water changes state, energy in the form of heat is either released or absorbed.
What is moisture content?
The ability of the atmosphere to hold moisture increases with temperature.
What are the three principles of the atmosphere?
Expansion, compression, mobility.
What is expansion in the atmosphere?
As air rises, it expands and cools
What is compression in the atmosphere?
Sinking air contracts and is heated.
What is gas law?
Cold air is more dense and tends to sink.
What is dew point?
The temperature at a given pressure to which air must be cooled to cause saturation (the state of the atmosphere in which air contains the maximum amount of water vapor that it can hold at a specific temperature and air pressure).
What happens when the dew point and temperature are the same?
The evaporation of water ceases/stops.
What is the difference between the temperature and the dew point called?
The spread.
What does the spread provide?
An indication of how close the air is to saturation (i.e. the temperatures being the same would indicate fog).
What is relative humidity?
Expresses the water vapour content in the air in percent (60%; the air is 60% saturated).
What happens at 100% relative humidity?
Air is completely saturated and water vapour will condense to water droplets to form cloud or fog.
What are the divisions of the atmosphere in order?
- Troposphere
- Stratosphere
- Mesosphere
- Thermosphere
What range of altitude does the troposphere cover?
from surface to 28,000ft over poles, and over 54,000ft over the equator.
Which division of the atmosphere does the weather mostly occur?
Troposphere.
What is true about the atmosphere in terms of pressure, temperature and density?
Pressure, temperature and density all decrease with altitude.
What is the top of the troposphere called?
The Tropopause.
What temperature is the tropopause at?
-56°C.
What temperature is the stratosphere?
Remains constant in lower portion 56°C.
At what height does the mesosphere go to?
275,000ft.
What happens to temperature through the mesosphere?
The point at which the temperature begins to increase called Mesopause.
What temperature range is the thermosphere in?
Increases to the 1000’s of degrees.
What occurs in the thermosphere?
The aurora (Northern Lights) occur in the layer.
What is solar radiation?
Energy emitted from sun as “short wave” ultraviolet (UV) radiation.
What percent of UV rays are absorbed by the ozone layer?
Approximately 19%.
What percent of UV rays is reflected back into space by the atmosphere?
6%.
What percent of UV rays is reflected back into space by cloud tops?
20%.
What percent of UV rays is reflected back into space by the earth’s surface?
4%.
What percent of UV rays are absorbed by the earth’s surface?
51%.
What are the 6 heating processes?
- Conduction
- Convection
- Turbulent mixing
- Advection
- Compression
- Release of latent heat
What is conduction?
Heating through contact, air is poor conductor, so limited in effect without other distribution processes
What is the equation for heating through contact (conduction)?
Warm ground + cool air + time = cooler ground + warmer air
What is convection (heating)?
Air that is warmed becomes less dense (gas law) and tends to rise.
What is turbulent mixing?
Friction causes eddies to form as air moves over surfaces (tall built up areas).
What is advection?
Horizontal movement of air masses.
If an air mass travels over a warm surface, what happens?
Air mass will be warmed; advection.
What is compression?
Descending (subsiding) air increases in pressure, in turn increasing temperature.
Where can compression occur?
Along ridges of high pressure or mountain ranges.
What is adiabatic heating?
When air descends in altitude it COMPRESSES and heats its adiabatic lapse rate.
What is adiabatic cooling?
When air rises in altitude it EXPANDS and cools at its adiabatic lapse rate.
What is lapse rate?
the rate at which an air warms or cools in response to altitude (pressure) changes.
What are the 7 cooling processes?
- Expansion
- Orographic & Upslope lift
- Frontal lift
- Mechanical turbulence
- Convection
- Convergence
- Advection & evaporation
What is expansion cooling?
Rising air decreases in temperature.
What is orographic & upslope lift?
The result of air flowing over topographical features that cause air to rise (warm body of water).
What is frontal lift?
Expansion cooling occurs when warm air is forced up along a frontal surface.
What is a cold front?
Advancing cold air displaces warmer air, causing it to rise quickly.
What is a warm front?
Advancing air cannot displace the cold air, so warm air gradually rises up and over the cold air.