STAGE 1 EXAM - meteorology
What is the temperature at sea level?
15 degrees Celsius
What is the standard lapse rate ?
2 degrees Celsius per 1000 increase in altitude
What is the air pressure at sea level (in inches of mercury)? psi? mb?
29.92" Hg 14.7 psi 1013.25 mb
The earths atmosphere is about __% nitrogen and __% oxygen
78% 21%
Define air pressure, air temperature, humidity and air density
Air pressure: the force of air above a given area or level Air temperature: the degree of hotness/coldness in the air. measure of avg kinetic energy of air molecules Humidity: a measure of the amount of water vapor in the air Air density: the mass of air in a given volume of space
What are the 7 elements of weather?
Air temperature, air pressure, humidity, clouds, precipitation, visibility, wind
What causes a radiation inversion?
Calm winds, Clear skies, Long nights
What are 3 ways to transfer heat around?
Conduction, Convection, radiation
What is the biggest killer of pilots?
Continued VFR into IFR conditions
What are the 4 different lifting processes?
Convection, Convergence, Weather Fronts, Topography
Unstable air characteristics
Cumuliform clouds, turbulent air, good visibility, heavy rain
what is the best indicator of the airs actual water vapor content?
Dew point
Which type of fog is formed by heating the air?
Evaporation fog
True or false: Air is a good conductor of heat
False
What is holding almost half of all the air molecules to the ground?
Gravity
What happens to latent heat during condensation?
Heat is released into the surroundings when the water vapor condenses to form liquid
What variables affect air density?
Humidity, pressure and temperature
define sublimation
Ice(solid) changes directly into gas without going through the liquid stage first
What two ways can you increase relative humidity?
Lowering the temperature & increasing water vapor in the air
Solid to Liquid is called
Melting
What are the 4 types of fog?
Radiation, Advection, Upslope, Evaporation
The air is considered to be ________________ when the level of water vapor in the air is the maximum possible at the existing temperature and pressure (in other words, 100% relative humidity)
Saturated
What 2 factors determine if the air will continue to rise or sink?
Stability and moisture content
Stable air characteristics
Stratus clouds, smooth air, fair to poor visibility, light drizzle rain
Air with Relative humidity greater than 100% is considered what?
Supersaturated
Seasons are caused by the earths tilt. The tilt regulates our seasons by affecting the amount of solar energy received at the earths surface. What two factors, caused by the earths tilt, affect the amount of solar energy received at a given general area at the surface?
The angle at which sunlight strikes the surface and the length of time the sun shines on any latitude (daylight hours)
What are seasons caused by?
The earth's tilt
define condensation
The process in which water vapor (gas) becomes liquid water
What happens to the temperature of the surrounding air during evaporation and sublimation and why?
The surroundings cool down because the heat energy was absorbed into the water molecule from the environment, therefore taking away heat from the surroundings and cooling it.
What happens to the temperature of the surrounding air during condensation and deposition and why?
The surroundings heat up because the heat energy previously absorbed is now being released back into the atmosphere, therefore warming the surroundings
what happens to the temperature of the surroundings during evaporation?
The surroundings will cool down
vertical air currents called __________ are caused by convection which is caused by....
Thermals; uneven heating of the earths surface
define conduction
Transfer of heat by molecular activity from one substance to another (molecule to molecule contact)
What layer of the atmosphere does almost all of our weather occur?
Troposphere
The air is considered to be ________________ when the level of water vapor in the air is less than the maximum possible at the existing temperature and pressure (in other words, less than 100% relative humidity)
Unsaturated
Define deposition
Vapor(gas) changes directly into ice(solid)without going through the liquid stage first
What gas can vary from 0% to 4% by volume in a given volume of air?
Water Vapor
What is an adiabatic process?
a process that takes place without a transfer of heat between the system and its surroundings.
what is the definition of a cloud?
a visible, aggregate of tiny water droplets and/or ice crystals in the atmosphere above the earths surface
How much sun energy is actually absorbed by the ground?
about half
what is formula for % relative humidity
amt of water vapor in the air / amt of water vapor it could have @ 100%
Define Precipation
any form of water particles, liquid or solid, that falls from the atmosphere and reaches the ground -rain, snow, sleet, freezing rain, hail, ice pellets, etc)
Define convection
atmospheric motions that are usually vertical, such as air rising currents due to surface heating
How are clouds GROUPED?
by height
How are clouds TYPED?
by shape and appearance
Gas to liquid is called
condensation
temperature ____________ as altitude _______________
decreases; increases
Liquid to Gas is called
evaporation
How is upslope fog formed?
formed when moist, stable air flows upward over a topographic barrier. chilling the air by pushing it upward
How is radiation fog formed?
formed when radiational cooling reduces the air temperature to or below its dew point
How is advection fog formed?
formed when warm, moist air moves over a cold surface and the air cools to below its dew point
Liquid to solid is called
freezing
What happens to latent heat during evaporation?
heat is absorbed from the surroundings into the eater vapor until its ready to condense back into a liquid
What does relative humidity tell us?
how close the air is to being saturated
What happens to air as it sinks?
it compresses and warms
What happens to air as it rises?
it expands and cools
the earth absorbs the suns energy (through shortwaves), heats up, and then emits this radiation back into the atmosphere in the form of _________________ radiation
longwave
What are the 4 cloud groups?
low, middle, high, vertically developed
How is evaporation fog formed?
produced when sufficient water vapor is added to the air by evaporation
Which 3 types of fog are formed by cooling the air down to its dew point?
radiation, Advection & Upslope fog
define radiation inversion
radiational cooling at the surface causes temperature to increase with height above the surface
Sun energy strikes the earth mostly in the form of ______________ radiation
shortwave
When lifted, the air tends to return to its original position, this means the air is...
stable
What determines how much water vapor the air can hold?
temperature -the warmer it is the more it can hold
Define latent heat
the heat that is either released or absorbed by a substance when it undergoes a change of state
Define evaporation
the process in which liquid water becomes water vapor (gas).
explain the moist adiabatic rate
the rate of change of temperature in a rising or descending SATURATED air parcel 1.8 degrees C/1000ft
explain the dry adiabatic rate
the rate of change of temperature in a rising or descending UNSATURATED air parcel 3 degrees C/1000ft
What is the primary source of energy for the earths surface?
the sun
What happens to the temperature of the surroundings during condensation?
the surroundings will heat up.
Define dew point
the temperature to which air would have to be cooled (with no change in air pressure or moisture content) for saturation to occur
Define advection
the transferring of properties from place to another by horizontally moving air
When lifted, the air will continue to rise, this means the air is...
unstable
Define temperature inversion
warm air above, cold air below
Define radiation
when the sun releases energy (shortwaves) which travel and release energy when absorbed by an object
