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Revision > flight : If a saturated air mass descends down a slope its temperature increases at ?

Question 132-1 : A lower rate than in dry air as evaporation absorbs heat the same rate as if the air mass were dry a lower rate than in dry air as condensation gives out heat a higher rate than in dry air as it gives up latent evaporation heat

.relative humidity will change if moisture is added to or taken from the air mass or if the temperature changes .if temperature increases relative humidity decreases and if temperature decreases relative humidity increases exemple 232 a lower rate than in dry air, as evaporation absorbs heat.a lower rate than in dry air, as evaporation absorbs heat.

Continuous freezing rain is observed at an airfield which of the four diagrams ?

Question 132-2 : Diagram 4 diagram 1 diagram 2 diagram 3

.there are a few basic elements that need to be in place for freezing rain to occur there must be a thick layer of warm air in the mid layers of the atmosphere there also must be a very narrow layer of below freezing temperatures at the surface . 545.the rain is falling into air with a temperature below 0°c exemple 236 diagram 4.diagram 4.

An isothermal layer is a layer of air in which the temperature ?

Question 132-3 : Remains constant with height increases with height decreases with height at a constant rate increases with height at a constant rate

exemple 240 remains constant with height.remains constant with height.

An inversion is a layer of air which is ?

Question 132-4 : Absolutely stable absolutely unstable conditionally unstable conditionally stable

exemple 244 absolutely stable.absolutely stable.

The environmental lapse rate in an actual atmosphere ?

Question 132-5 : Varies with time has a fixed value of 1°c/100m has a fixed value of 0 65°c/100m has a fixed value of 2°c/1000 ft

exemple 248 varies with time.varies with time.

The dry adiabatic lapse rate has a value of ?

Question 132-6 : 1°c/100 m 2°c/1000 ft 0 65°c/100 m 0 5°c/100 m

.the dry adiabatic lapse rate has a constant fixed value of 1°c/100 m 3°c/1000 ft exemple 252 1°c/100 m.1°c/100 m.

The dry adiabatic lapse rate ?

Question 132-7 : Has a constant fixed value is greater in summer than in winter is greater during the night than during the day has a variable value

.the dry adiabatic lapse rate has a constant fixed value of 1°c/100 m 3°c/1000 ft exemple 256 has a constant fixed value.has a constant fixed value.

An air mass is called stable when ?

Question 132-8 : The vertical motion of rising air tends to become weaker and disappears the temperature in a given air mass decreases rapidly with height the pressure in a given area is constant the environmental lapse rate is high with little vertical motion of air currents

exemple 260 the vertical motion of rising air tends to become weaker and disappearsthe vertical motion of rising air tends to become weaker and disappears

Advection is ?

Question 132-9 : Horizontal motion of air vertical motion of air the same as subsidence the same as convection

.advection is horizontal motion of air.subsidence is vertically downwards motion of air.convection is vertically upwards motion of air exemple 264 horizontal motion of air.horizontal motion of air.

Subsidence is ?

Question 132-10 : Vertically downwards motion of air horizontal motion of air vertically upwards motion of air the same as convection

.advection is horizontal motion of air.subsidence is vertically downwards motion of air.convection is vertically upwards motion of air exemple 268 vertically downwards motion of air.vertically downwards motion of air.

Rising air cools because ?

Question 132-11 : It expands surrounding air is cooler at higher levels it becomes more moist it contracts

exemple 272 it expands.it expands.

A layer can be ?

Question 132-12 : Stable for unsaturated air and unstable for saturated air stable for saturated air and unstable for unsaturated air unstable for unsaturated air and neutral for saturated air unstable for unsaturated air and conditionally unstable

.if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable.if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable.but.if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry unsaturated .or. unstable if air is saturated exemple 276 stable for unsaturated air and unstable for saturated air.stable for unsaturated air and unstable for saturated air.

In a layer of air the decrease in temperature per 100 metres increase in height ?

Question 132-13 : Absolutely unstable absolutely stable conditionally unstable conditionally stable

.more than 1°c/100 m = more than 3°c/1000 ft.if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable.if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable.if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry unsaturated .or. unstable if air is saturated exemple 280 absolutely unstable.absolutely unstable.

Which statement is true for a conditionally unstable layer ?

Question 132-14 : The environmental lapse rate is less than 1°c/100 m the environmental lapse rate is less than 0 65°c/100 m the layer is unstable for unsaturated air the wet adiabatic lapse rate is 0 65°c/100 m

.more than 1°c/100 m = more than 3°c/1000 ft.if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable.if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable.if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry unsaturated .or. unstable if air is saturated exemple 284 the environmental lapse rate is less than 1°c/100 m.the environmental lapse rate is less than 1°c/100 m.

The stability in a layer is increasing if ?

Question 132-15 : Warm air is advected in the upper part and cold air in the lower part warm air is advected in the lower part and cold air in the upper part warm and moist air is advected in the lower part cold and dry air is advected in the upper part

.it is similar to an inversion .if a parcel of air is forced to rise it will be colder than the air it is rising into so the moment the trigger stops lifting it it will sink back to the level it started from because it is more dense the layer is stable exemple 288 warm air is advected in the upper part and cold air in the lower part.warm air is advected in the upper part and cold air in the lower part.

Which of the following statements concerning the lifting of a parcel of air is ?

Question 132-16 : Unsaturated parcels cool more rapidly than saturated parcels unsaturated parcels cool less rapidly than saturated parcels unsaturated parcels cool at a rate of 0 65°c per 100 m saturated parcels always cool at a rate of 0 65°c per 100 m

.there is less moisture in an unsaturated parcels to retain heat exemple 292 unsaturated parcels cool more rapidly than saturated parcels.unsaturated parcels cool more rapidly than saturated parcels.

When in the upper part of a layer warm air is advected the ?

Question 132-17 : Stability increases in the layer stability decreases in the layer wind will back with increasing height in the northern hemisphere wind speed will always decrease with increasing height in the northern hemisphere

.it is similar to an inversion .if a parcel of air is forced to rise it will be colder than the air it is rising into so the moment the trigger stops lifting it it will sink back to the level it started from because it is more dense the stability increases in the layer exemple 296 stability increases in the layer.stability increases in the layer.

The dew point temperature ?

Question 132-18 : Can be equal to the air temperature is always lower than the air temperature is always higher than the air temperature can not be equal to the air temperature

exemple 300 can be equal to the air temperature.can be equal to the air temperature.

Relative humidity depends on ?

Question 132-19 : Moisture content and temperature of the air moisture content and pressure of the air moisture content of the air only temperature of the air only

exemple 304 moisture content and temperature of the airmoisture content and temperature of the air

When water evaporates into unsaturated air ?

Question 132-20 : Heat is absorbed heat is released relative humidity is not changed relative humidity is decreased

.a known phenomena when water evaporates into unsaturated air is that the air is cooled the water transitioning from a liquid state to a gaseous state is transitioning from a lower energy state to a higher energy state the energy required for this transition to take place is provided to the water in the form of heat that is taken out of the surrounding air this latent heat of vaporization leaving the air causes a temperature of the air to be reduced exemple 308 heat is absorbed.heat is absorbed.

A moist but unsaturated parcel of air becomes saturated by ?

Question 132-21 : Lifting the parcel to a higher level lowering the parcel to a lower level moving the parcel to an area with lower pressure and equal temperature moving the parcel to an area with higher pressure and equal temperature

.air can hold a certain amount of water depending on it's temperature warmer air can hold more water vapour than colder air .thus by cooling the air it can hold less water vapour and the relative humidity increases how does air cool usually by increasing in height.so to get an unsaturated parcel of air with say 40% of relative humidity to 100% of relative humidity fully saturated a cloud then you must cool the parcel by lifting it to a higher level exemple 312 lifting the parcel to a higher level.lifting the parcel to a higher level.

A sample of moist but unsaturated air may become saturated by ?

Question 132-22 : Expanding it adiabatically raising the temperature lowering the pressure keeping temperature constant compressing it adiabatically

Fabricet .don't get why an unsaturated air mass could become saturated by expanding it adiabatically by compressing it the relative humidity will increase until reaching the 100% of humidity making the air mass saturated. .if you compress it it will heat up and if you expand it will cool .during an adiabatic process heat is neither added nor lost air can hold a certain amount of water depending on it's temperature warmer air can hold more water vapour than colder air .thus by cooling the air it can hold less water vapour and the relative humidity increases how does air cool usually by increasing in height .so to get an unsaturated parcel of air with say 40% of relative humidity to 100% of relative humidity fully saturated a cloud then you must cool the parcel by lifting it to a higher level when it expands adiabatically it cools so relative humidity must increase exemple 316 expanding it adiabatically.expanding it adiabatically.

The maximum amount of water vapour that the air can contain depends on the ?

Question 132-23 : Air temperature relative humidity stability of the air dewpoint

.the most commonly used measure of humidity is relative humidity relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100 air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature . 501. concept of relative humidity.we can say that the amount of water vapour which air can hold largely depends on air temperature exemple 320 air temperature.air temperature.

Convective clouds are formed ?

Question 132-24 : In unstable atmosphere in stable atmosphere in summer during the day only in mid latitudes only

exemple 324 in unstable atmosphere.in unstable atmosphere.

The most effective way to dissipate cloud is by ?

Question 132-25 : Subsidence convection a decrease in temperature a decrease in pressure

exemple 328 subsidence.subsidence.

Areas of sinking air are generally cloudless because as air sinks it ?

Question 132-26 : Is heated by compression reaches warmer layers is heated by expansion loses water vapour

.as the air sinks to lower levels the pressure increases which compresses the air increasing density and temperature .as the air temperature increases its capacity to hold water vapour increases and relative humidity decreases exemple 332 is heated by compression.is heated by compression.

The main factor which contributes to the formation of very low clouds ahead of ?

Question 132-27 : Saturation of the cold air by rain falling into it and evaporating saturation of the warm air by rain falling into it and evaporating reduction of outgoing radiation due to clouds warm air moving over a cold surface

.clouds form in the front rain falls from them out of the warm sector into the cold sector . 559.latent heat is absorbed when going from liquid to gas vapour at low levels you will have stratus and nimbostratus clouds exemple 336 saturation of the cold air by rain falling into it and evaporating.saturation of the cold air by rain falling into it and evaporating.

In an unstable layer there are cumuliform clouds the vertical extent of these ?

Question 132-28 : Thickness of the unstable layer wind direction air pressure at the surface pressure at different levels

exemple 340 thickness of the unstable layerthickness of the unstable layer

Which of the following phenomena are formed when a moist stable layer of air is ?

Question 132-29 : Stratified clouds inversions showers and thunderstorms areas of severe turbulence

.lifting moist stable layer of air produces stratus exemple 344 stratified clouds.stratified clouds.

The height of the lifting condensation level is determined by ?

Question 132-30 : Temperature and dewpoint at the surface temperature at surface and air pressure wind and dewpoint at the surface wet adiabatic lapse rate and dewpoint at the surface

. 560.the height of a cloud base that results from lifting of near surface air can be estimated based on the surface values of temperature and dew point since the height at which a cloud will form is roughly the height at which the temperature and dew point would become equal due to expansion of the air as it rises to regions of lower pressure exemple 348 temperature and dewpoint at the surface.temperature and dewpoint at the surface.

During an adiabatic process heat is ?

Question 132-31 : Neither added nor lost added lost added but the result is an overall loss

exemple 352 neither added nor lost.neither added nor lost.

The decrease in temperature per 100 metres in an unsaturated rising parcel of ?

Question 132-32 : 1°c 2°c 0 65°c 0 5°c

.1°c/100 m or 3°c/1000 ft this is the dry adiabatic lapse rate exemple 356 1°c.1°c.

The decrease in temperature per 100 metres in a saturated rising parcel of air ?

Question 132-33 : 0 6°c 1°c 1 5°c 0 35°c

.dry lapse rate = 3ºc/1000 ft or 1ºc/100 m.saturated lapse rate = 1ºc/1000 ft or 0 6ºc/100 m exemple 360 0.6°c.0.6°c.

In unstable air ground visibility is most likely to be restricted by ?

Question 132-34 : Showers of rain or snow haze drizzle low stratus

exemple 364 showers of rain or snow.showers of rain or snow.

A vertical temperature profile indicates the possibility of severe icing when ?

Question 132-35 : Intersects the 0°c isotherm twice coincides with a dry adiabatic lapse rate indicates temperatures below 40°c indicates temperatures above 3°c

.to intersect the 0ºc isotherm twice there must be warm air above cold air this occurs at a warm front and is where rain ice will be encountered exemple 368 intersects the 0°c isotherm twice.intersects the 0°c isotherm twice.

The rate of cooling of ascending saturated air is less than the rate of cooling ?

Question 132-36 : Heat is released during the condensation process moist air is heavier than dry air water vapour doesn't cool as rapidly as dry air water vapour absorbs the incoming heat from the sun

exemple 372 heat is released during the condensation process.heat is released during the condensation process.

If the surface temperature is 15°c then the temperature at 10000 ft in a ?

Question 132-37 : 15°c 0°c 5°c 5°c

. ascending unsaturated air means dry adiabatic lapse rate and we know that the environmental lapse rate elr is more than 3°c/1000ft for dry adiabatic lapse rate.15°c 3° x 10 = 15°c exemple 376 -15°c.-15°c.

An inversion is ?

Question 132-38 : An increase of temperature with height an increase of pressure with height a decrease of pressure with height a decrease of temperature with height

exemple 380 an increase of temperature with heightan increase of temperature with height

In still air the temperature decreases at an average of 1 2°c per 100 m ?

Question 132-39 : Dry adiabatic lapse rate saturated adiabatic lapse rate environmental lapse rate normal lapse rate

.if the environmental lapse rate elr is more than 3°c/1000 ft dry adiabatic lapse rate the environment is unstable.if the environmental lapse rate elr is less than 1 8°c/1000 ft saturated adiabatic lapse rate the environment is stable.if the environmental lapse rate elr is more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability . stable if air is dry .or. unstable if air is saturated.1 2°c per 100m is 3 6°c per 1000 ft .the environmental lapse rate elr is more than 3°c/1000 ft this temperature change is called 'dry adiabatic lapse rate' exemple 384 dry adiabatic lapse rate.dry adiabatic lapse rate.

From which of the following pieces of information can the stability of the ?

Question 132-40 : Environmental lapse rate dry adiabatic lapse rate surface temperature pressure at the surface

.if the environmental lapse rate elr is more than 3°c/1000ft dry adiabatic lapse rate the environment is unstable.if the environmental lapse rate elr is less than 1 8°c/1000ft saturated adiabatic lapse rate the environment is stable.if the environmental lapse rate elr is more than 1 8°c/1000ft but less than 3°c/1000ft we have conditional stability . stable if air is dry .or. unstable if air is saturated exemple 388 environmental lapse rate.environmental lapse rate.

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