HUMIDITY PRACTICE QUESTIONSDGCA QUESTIONS BANK FOR PILOTS HUMIDITY 1 MCQ QUESTION OF HUMIDITY 1 1 / 23 1. Relative humidity depends on moisture content of the air only temperature of the air only moisture content and temperature of the air moisture content and pressure of the air Absolute Humidity is the weight of water vapour in unit volume of air. Absolute Humidity is usually expressed in gm/m3.Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water. Relative humidity is expressed as a percentage 2 / 23 2. When a given mass of air descends, what effect will it have on relative humidity? It increases. It remains constant. It increases up to 100%, and then remains stable It decreases. As the air descends it will be heated adiabatically and will be warmer than the air at a lower level adjacent to the surface.as the temperature increases, the relative humidity will decrease 3 / 23 3. What does dewpoint mean? The freezing level (danger of icing). The temperature at which the relative humidity and saturation vapour pressure are the same. The temperature to which a mass of air must be cooled in order to reach saturation. The temperature at which ice melts. The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapour component to condense into water. The dew point of unsaturated air decreases by approximately 0.5°C per 1,000 ftThe dew point is associated with the relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. 4 / 23 4. Relative humidity at a given temperature is the relation between: water vapour weight and humid air volume dew point and air temperature actual water vapour content and saturated water vapour content water vapour weight and dry air weight Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water. Relative humidity is expressed as a percentage and is calculated using the formula below. More simply, the relative humidity is the amount of water vapour present in a volume of air divided by the maximum amount of water vapour which that volume could hold at that temperature expressed as a percentage. 5 / 23 5. The maximum amount of water vapour that the air can contain depends on the: air temperature relative humidity stability of the air dewpoint This amount of space in the air that can hold water changes depending on the temperature and pressure.The maximum amount of water vapour that can be in the air depends on the air temperature 6 / 23 6. Which of the following changes of state is known as sublimation? Solid direct to liquid Liquid direct to solid Liquid direct to vapour Solid direct to vapour FreezingIf the water droplet is cooled below zero, then it may change state again to ice.MeltingThe opposite change of state, from solid to liquid, is called meltingSublimation/DepositionSublimation is the change of state directly from water vapour to ice without water droplets being formed. Latent heat is released. This process is also known as deposition.The change of state from ice directly to water vapour is also called sublimation. 7 / 23 8. Which of the following statements is true of the dew point of an air mass? It can only be equal to, or lower, than the temperature of the air mass It can be higher than the temperature of the air mass It can be used together with the air pressure to estimate the air mass’s relative humidity It can be used to estimate the air mass’s relative humidity even if the air temperature is unknown The dew point is associated with the relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. If the relative humidity is 100%, the dew point will be equal to the current temperature. The dew point can never be more than the ambient temperature 8 / 23 7. When water evaporates into unsaturated air: heat is absorbed heat is released relative humidity is not changed relative humidity is decreased Unsaturated air can also be called dry airi.e RH less than 100%, if water evaporates into unsaturated air heat is absorbed 9 / 23 9. The process by which water vapour is transformed directly into ice is known as: sublimation supercooling supersaturation radiation cooling Sublimation/DepositionSublimation is the change of state directly from water vapour to ice without water droplets being formed. Latent heat is released. This process is also known as deposition.The change of state from ice directly to water vapour is also called sublimation. 10 / 23 10. During the late afternoon an air temperature of +12°C and a dew point of +5°C were measured. What temperature change must occur during the night in order to induce saturation? It must decrease to +7°C. It must decrease to +5°C. It must decrease by 5°C. It must decrease to +6°C. When temperature and dew point are same saturation occurs and fog formation takes place 11 / 23 11. Dew point is defined as: the temperature below which the change of state in a given volume of air will result in the absorption of latent heat the temperature to which moist air must be cooled to become saturated at a given pressure the lowest temperature at which evaporation will occur for a given pressure the lowest temperature to which air must be cooled in order to reduce the relative humidity The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for the water vapour component to condense into water. The dew point of unsaturated air decreases by approximately 0.5°C per 1,000 ftThe dew point is associated with the relative humidity. A high relative humidity indicates that the dew point is closer to the current air temperature. 12 / 23 12. How, if at all, is the relative humidity of an unsaturated air mass influenced by temperature changes? It increases with increasing temperature. It is only influenced by the amount of water vapour. It decreases with increasing temperature. It is not influenced by temperature changes Relative humidity is inversely proportional to unsaturated air mass 13 / 23 13. Relative humidity: increases if the air is cooled whilst maintaining the vapour pressure constant is higher in warm air than in cool air is higher in cool air than in warm air decreases if the air is cooled whilst maintaining the vapour pressure constant As the air descends it will be heated adiabatically and will be warmer than the air at a lower level adjacent to the surface.as the temperature increases, the relative humidity will decrease vice aversetemp decreases rh increases 14 / 23 14. In which of the following changes of state is latent heat released? Gas to liquid Solid to liquid Solid to gas Liquid to gas Condensation is the change of state from vapour to liquid. Latent heat is released. If the water vapour is returned to a liquid or solid phase (by condensation or deposition), the stored energy is released as sensible heat onto the surface where condensation 15 / 23 15. The dewpoint temperature: can be reached by cooling the air whilst keeping pressure constant can be reached by lowering the pressure whilst keeping temperature constant can not be equal to the air temperature can not be lower than the air temperature The dew point or dewpoint of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, 16 / 23 16. Which of the following is the definition of relative humidity? Ratio between water vapour pressure and atmospheric pressure X 100 Ratio between water vapour (g) and air (kg) X 100 Ratio between the actual mixing ratio and the saturation mixing ratio X 100 Ratio between air temperature and dewpoint temperature X100 Humidity Mixing Ratio (HMR) is the weight of water vapour contained in unit mass of dry air. 17 / 23 17. The difference between temperature and dewpoint is greater in: moist air air with high temperature air with low temperature dry air If the relative humidity is 100%, the dew point will be equal to the current temperature.in dry air RH Is less than 100% lesser the rh more the difference 18 / 23 18. A parcel of moist but not saturated air rises due to adiabatic effects. Which of the following changes? Mixing ratio Specific humidity Relative humidity Absolute humidity relative humidity depends on temperature and pressure , with change in height, pressure and temperature will reduce and rh will change 19 / 23 19. Relative humidity: does not change when water vapour is added provided the temperature of the air remains constant changes when water vapour is added, even though the temperature remains constant is not affected when air is ascending or descending. is not affected by temperature changes of the air Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water. water vapour increases rh changes 20 / 23 20. The relative humidity of a sample air mass is 50%. How is the relative humidity of this air mass influenced by changes of the amount of water vapour in it? It decreases with increasing water vapour It is only influenced by temperature It increases with increasing water vapour It is not influenced by changing water vapour Relative Humidity is a term used to describe the quantity of water vapour that exists in a gaseous mixture of air and water. water vapour increases rh increases 21 / 23 21. How does relative humidity and the dewpoint in an unsaturated air mass change with varying temperature? When temperature increases, the relative humidity decreases, and the dewpoint remains constant. When temperature increases, the relative humidity increases, and the dewpoint decreases. When temperature decreases, the relative humidity decreases, and the dewpoint increases When temperature decreases, the relative humidity and the dewpoint remain constant Relative humidity is inversely proportional to unsaturated air mass dew point will remain same 22 / 23 22. In which layer is most of the atmospheric humidity concentrated? Stratosphere Stratopause. Troposphere. Tropopause. Troposphere has moisture content, because of which cloud formation and weather takes place here 23 / 23 23. The dewpoint temperature can not be equal to the air temperature can be equal to the air temperature is always lower than the air temperature is always higher than the air temperature A high relative humidity indicates that the dew point is closer to the current air temperature.If the relative humidity is 100%, the dew point will be equal to the current temperature.The dew point can never be more than the ambient temperature. Your score isThe average score is 0% 0% Restart quiz