A layer is absolutely unstable if the temperature decrease with height is ?
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A layer in which the temperature remains constant with height is ?
A layer in which the temperature increases with height is ?
A layer in which temperature decreases with 1°c per 100 m increasing altitude More than °c per m. lapse rate 1°c 100 m (1° per 328 ft) so 3°/1000 ft we have four possibilities if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) environment stable if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability if air dry or unstability if air saturated the question states 1°c per 100m it not more or not less than 3°c/1000 ft it will be neutral dry air. 
If in a 100 m thick layer temperature at bottom of layer 10°c and at top of layer 8°c then this layer More than °c per m. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) environment stable if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry or unstable if air saturated in our layer environmental lapse rate 2°c/300 ft (or around 6°c/1000 ft ) which absolutely unstable. 
A wide body takes off on a clear night in dhahran saudi arabia shortly after take off aircraft's rate of climb drops to zero this can be due to A very strong temperature inversion. the question states 'clear night' we can exclude sand or dust in engines very pronounced downdrafts might be a acceptable answer but it means unstable air clouds it can't be a clear night humidity will not sufficiently affect lift engine power to visually decrease rate of climb during night radiation will cool surface which then cools air close to surface the air temperature at 3 4000 ft air still very warm this a very strong temperature inversion (less density less lift less power). 
The value of saturated adiabatic lapse rate closest to that of dry adiabatic lapse rate in A very strong temperature inversion. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) the environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) the environment stable if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry or unstable if air saturated as we go up in atmosphere air gets colder the dry adiabatic lapse rate the saturated adiabatic lapse rate become closer because moisture varies (the colder air mass is lesser moisture it can contain) cirrus clouds are located at high levels near lowest temperatures of troposphere. Question 133-8
Dew point defined as The temperature to which moist air must be cooled to become saturated at a given pressure. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) the environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) the environment stable if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry or unstable if air saturated as we go up in atmosphere air gets colder the dry adiabatic lapse rate the saturated adiabatic lapse rate become closer because moisture varies (the colder air mass is lesser moisture it can contain) cirrus clouds are located at high levels near lowest temperatures of troposphere. Question 133-9
The process which water vapour transformed directly into ice known as The temperature to which moist air must be cooled to become saturated at a given pressure. the answer should be 'deposition' sublimation ice to water vapour deposition water vapour to ice but expression 'sublimation' may be be used both processes. Question 133-10
A foehn wind occurs on Leeward side of a mountain range is caused significant moisture loss precipitation from cloud. the answer should be 'deposition' sublimation ice to water vapour deposition water vapour to ice but expression 'sublimation' may be be used both processes. Question 133-11
Relative humidity at a given temperature the relation between Actual water vapour content saturated water vapour content. the answer should be 'deposition' sublimation ice to water vapour deposition water vapour to ice but expression 'sublimation' may be be used both processes. Question 133-12
A parcel of unsaturated air forced to rise through an isothermal layer so long as it remains unsaturated temperature of parcel Decreases °c per m. unsaturated air forced to rise (ascending) mean dry adiabatic lapse rate we know that environmental lapse rate (elr) more than 3°c/1000ft dry adiabatic lapse rate (1°c 100 m). Question 133-13
Absolute instability in atmosphere will occur when environmental lapse rate Greater than both saturated adiabatic lapse rate dry adiabatic lapse rate. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) environment stable but if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry (unsaturated) or unstable if air saturated. Question 133-14
For both saturated and unsaturated air instability will occur when Environmental lapse rate greater than both dry adiabatic lapse rate saturated adiabatic lapse rate. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) environment stable but if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry (unsaturated) or unstable if air saturated. Question 133-15
In lower levels of atmosphere when environmental lapse rate greater than saturated adiabatic lapse rate but less than dry adiabatic lapse rate air mass described as being Conditionally unstable. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) less than 1 8°c/1000 ft (saturated adiabatic lapse rate) environment stable but if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry (unsaturated) or unstable if air saturated. Question 133-16
Surface temperature inversions are frequently generated Terrestrial radiation on a calm clear night. the cooling of land after sunset thermal radiation in calm conditions with clear sky will generate ground inversions. Question 133-17
Surface based temperature inversions are common during Cloud free nights in winter when ground dry. a temperature inversion a thin layer of atmosphere where normal decrease in temperature with height switches to temperature increasing with height a long clear winter night will lead to surface temperature inversion (radiation inversion between surface up to 500 ft). Question 133-18
The maximum vapour pressure over a flat supercooled water surface and maximum vapour pressure over a flat ice surface of same temperature are compared the maximum vapour pressure Greater over water surface. the maximum vapour pressure greater over water surface because it easier the flat supercooled liquid water to change state into vapour the flat ice surface has to sublimate into vapour (there will be more molecules of water vapour in atmosphere over supercooled water than over ice pressure will be greater). Question 133-19
The stability in a layer increases advection of Cold air in lower part. the stability of atmosphere depends on its ability to resist vertical motion there are 2 things to have a look at moisture advection temperature advection a moisture advection since water vapour lighter than air moisture decreases air density causing it to rise since moist air cools at a slower rate it generally less stable than dry air since moist air must rise higher before its temperature cools to that of surrounding air the dry adiabatic lapse rate (unsaturated air) 3°c per 1000 feet the moist adiabatic lapse rate varies from 1 8°c to 3°c per 1000 feet it's not answer moist air in lower part dry air heavier will want to sink therefore dry air aloft decreases stability as less dry air below will tend to rise replace it it's not answer dry air in upper part b temperature advection advecting warm air in lower parts of troposphere will make parcel warmer than its surrounding therefore it'll keep rising it's not answer warm air in lower part conclusion the combination of moisture temperature determine stability of air cool dry air very stable resists vertical movement the greatest instability occurs when air moist warm as it in tropical regions in summer correct answer cold air in lower part. Question 133-20
The temperature at surface given as +15°c and at 4000 ft it +9°c state of this layer said to be Cold air in lower part. between surface 4000 ft temperature drops 6°c or 1 5°c per 1000 ft if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable if environmental lapse rate (elr) is less than 1 8°c/1000 ft (saturated adiabatic lapse rate) the environment stable if environmental lapse rate (elr) more than 1 8°c/1000 ft but less than 3°c/1000 ft we have conditional stability stable if air dry or unstable if air saturated. Question 133-21
Which of following phenomena least likely to lead to formation of a cumulonimbus with thunderstorm Cold air in lower part. convection convergence orographic lift can all lead to formation of a cumulonimbus with thunderstorm ground radiation will dissipate clouds or generate a convective activity may sometimes create cumulus clouds. Question 133-22
Which of following sets of conditions are most favourable to development of thunderstorms Environmental lapse rate greater than saturated adiabatic lapse rate through a great vertical extent high relative humidity an initial lifting process. convection convergence orographic lift can all lead to formation of a cumulonimbus with thunderstorm ground radiation will dissipate clouds or generate a convective activity may sometimes create cumulus clouds. Question 133-23
Which of following statements correct The bergeron findeisen process mainly based on difference of maximum vapour pressure over water over ice of same temperature. the saturation vapour pressure higher over water than over ice what that means that you will reach frost point before you reach dew point bergeron showed that in mid latiudes because it cold inside clouds precipitation caused mainly the coalence of water vapour onto ice crystals it does not explain everything is just one of theories of precipitation if there are no nuclei present you can raise relative humidity to 460% before a drop will form spontaneously (super saturation). Question 133-24
Which of following statements true of dew point of an air mass It can only be equal to or lower than temperature of air mass. the dewpoint temperature the temperature at which air can no longer hold all of its water vapor some of water vapor must condense into liquid water the dew point always lower than (or equal to) air temperature if air temperature cools to dew point or if dew point rises to equal air temperature then dew fog or clouds begin to form at this point where dew point temperature equals air temperature relative humidity 100%. Question 133-25
Which one of following can provide initial lifting leading to air mass thunderstorms Advection of cold air over a warm sea. cold air over a warm surface gives convective lifting. Question 133-26
Which of following quantities remains unchanged if unsaturated air lifted until it reaches lifting condensation level Advection of cold air over a warm sea. if unsaturated air (dry adiabatic lapse rate) lifted until it reaches lifting condensation level ratio of water vapour to air mass (called 'mass ratio' or 'mixing ratio') will remained unchanged the mixing ratio of water vapor in air used to describe humidity. Question 133-27
Which of following processes will increase stability of an air mass Cooling the underlying surface. if unsaturated air (dry adiabatic lapse rate) lifted until it reaches lifting condensation level ratio of water vapour to air mass (called 'mass ratio' or 'mixing ratio') will remained unchanged the mixing ratio of water vapor in air used to describe humidity. Question 133-28
Which statement correct an absolutely unstable atmosphere Visibility good between showers. if environmental lapse rate (elr) more than 3°c/1000 ft (dry adiabatic lapse rate) environment unstable stable air will produce stratiform cloud unstable air mass produces showers under cumulonimbus clouds outside showers visibilty good. Question 133-29
Relative humidity Increases if air cooled whilst maintaining vapour pressure constant. the air contracts therefore takes less volume the water quantity does not change (maintaining vapour pressure constant' ) thus relative humidity increases. Question 133-30
What true the water vapour distribution in layer between surface and 500 hpa pressure surface in tradewind belt The lower part relatively moist the upper part relatively dry. 500 hpa = fl 180 se trade winds ne trade winds converge at itcz (intertropical convergence zone) they occur only in lower part of troposphere are more pronounced over oceans in trade winds there a maximum of humidity as a result of trade winds long sea passage in upper part air originates from sub tropical high pressure belt sinking warming adiabatically if temperature increases relative humidity will decrease upper part relatively dry. Question 133-31
What the dry adiabatic lapse rate The lower part relatively moist the upper part relatively dry. the dry adiabatic lapse rate has a constant fixed value of 1°c/100 m (3°c/1000 ft). Question 133-32
What a characteristic of stable air The lower part relatively moist the upper part relatively dry. the dry adiabatic lapse rate has a constant fixed value of 1°c/100 m (3°c/1000 ft). Question 133-33
What a characteristic phenomenon a stable atmosphere The lower part relatively moist the upper part relatively dry. the words to distinguish between clouds produced instability other clouds are stratiform/stratified clouds forming in a stable layer convective clouds clouds developing in an unstable environment stratiform clouds are basically flat layered stable clouds include cirrostratus altostratus nimbostratus stratus convective clouds have vertical development often extend through a significant depth of troposphere convective clouds include cumulonimbus cumulus cirrus altocumulus. Question 133-34
In an unsaturated layer in friction layer air well mixed turbulence the layer remains unsaturated after some time vertical temperature profile will Correspond to dry adiabatic lapse rate. if layer remains unsatured we have a conditional stability (depending on dry or satured air) but mixing temperature in turbulence layer will change vertical temperature profile increasing vertical rate of temperature change it will correspond to dry adiabatic lapse rate. Question 133-35
Good visibility in lower levels may be expected when Cool dry air moving over a warmer surface. good visibility associated with unstable air a cool dry air moving over a warm surface will become unstable. Question 133-36
A layer of stratus most likely to be dispersed Insolation resulting in lifting of condensation level. good visibility associated with unstable air a cool dry air moving over a warm surface will become unstable. Question 133-37
After a clear night cumuliform clouds are formed in morning why can base of these clouds become higher during day Because surface temperature increases. good visibility associated with unstable air a cool dry air moving over a warm surface will become unstable. Question 133-38
Air masses which are being cooled from below are often characterized Fog poor visibility layered clouds. good visibility associated with unstable air a cool dry air moving over a warm surface will become unstable. Question 133-39
An inversion An absolutely stable layer. good visibility associated with unstable air a cool dry air moving over a warm surface will become unstable. Question 133-40
An unstable air mass forced to ascend a mountain slope what type of clouds can be expected Clouds with considerable vertical development associated turbulence. unstable air = cumulus stable air = stratus this question has been seen at exam with this wording «a conditionally unstable air mass forced to ascend a mountain slope what type of clouds can be expected?» right answer remains unchanged.
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