Physics · Geography

Atmospheric Physics and Humidity

935 Questions

Study the principles of atmospheric physics and humidity through these practice questions. Key subjects include the rate of evaporation, temperature inversions, and relative humidity measurements. These concepts are vital for geography and physics exams.

Evaporation and condensationRelative humidity conceptsAtmospheric pressure effectsTemperature inversion

Atmospheric Physics and Humidity Questions

Multiple choice

The dispersion of pollutants in atmosphere is maximum when

  1. environmental lapse rate is greater than adiabatic lapse rate

  2. environmental lapse rate is less than adiabatic lapse rate

  3. environmental lapse rate is equal to adiabatic lapse rate

  4. maximum mixing depth is equal to zero
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

 Unstable environment means ELR > ALR.

(ELR = Environment Lapse rate, ALR = Adiabatic Lapse Rate)

A rising air parcel will continue to go up and dispersion of pollutant will be rapid due to vertical mixing of air with pollutants.

Multiple choice

Moist air at 35oC and 100% relative humidity is entering a psychrometric device and leaving at 25oC and 100% relative humidity. The name of the device is

  1. Humidifier

  2. Dehumidifier

  3. Sensible heater

  4. Sensible cooler
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Correct option is (2).

By drawing intel and outlet points in Psychometric chart. We can see that as we move down on Psychometric line humidity also goes down. So this Psychometric device is working as Dehumidifier.

Multiple choice

A room contains 35 kg of dry air and 0.5 kg of water vapour. The total pressure and temperature of air in the room are 100 kPa and 250C respectively. Given that the saturation pressure for water at 250C is 3.17 kPa, the relative humidity of the air in the room is

  1. 67%

  2. 55%

  3. 83%

  4. 71%
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$\text{We have} \hspace{0.2cm} m_a = 35kg, m_v = 0.5kg, p_t = 100 kPa \hspace{0.2cm} and \hspace{0.2cm} p_{vs} = 3.17 kPa. \\ \text{Specific humidity} \hspace{0.5cm} W = \frac{m_v}{m_a} = \frac{0.5}{35} = 0.01428$

Multiple choice

In an experimental set-up, air flows between two stations P and Q adiabatically. The direction of flow depends on the pressure and temperature conditions maintained at P and Q. The conditions at station P are 150 kPa and 350 K. The temperature at station Q is 300 K. The following are the properties and relations pertaining to air: Specific heat at constant pressure, Cp = 1.005 kJ/kgK; Specific heat at constant volume, Cv = 0.718 kJ/kgK; Characteristic gas constant, R = 0.287 kJ/kgK Enthalpy, h = cp T Internal energy, u = Cv T

If the pressure at station Q is 50 kPa, the change in entropy (sQ - sP ) in kJ/kgK is

  1. -0.155

  2. 0

  3. 0.160

  4. 0.355
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

A thin layer of water in field is formed after a farmer has watered it. The ambient air conditions are: temperature 20°C and relative humidity 5%. An extract of steam tables is given below |||||||||| |---|---|---|---|---|---|---|---|---| | Temperature (oC)| - 15| - 10| - 5| 0.01| 5| 10| 15| 20| | Saturation pressure (kPa)| 0.10| 0.26| 0.40| 0.61| 0.87| 1.23| 1.71| 2.34|

Neglecting the heat transfer between the water and the ground, the water temperature in the field after phase equilibrium is reached equals

  1. 10.3°C

  2. -10.3°C

  3. -14.5°C

  4. 14.5°C
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Multiple choice

The statement concern psychrometric chart.

  1. Constant relative humidity lines are uphill straight lines to the right.
  2. Constant wet bulb temperature lines are downhill straight lines to the right.
  3. Constant specific volume lines are downhill straight lines to the right.
  4. Constant enthalpy lines are coincident with constant wet bulb temperature lines. Which of the statements are correct?

  1. 2 and 3

  2. 1 and 2

  3. 1 and 3

  4. 2 and 4
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multiple choice

Water at 42° is sprayed into a stream of air at atmospheric pressure, dry bulb temperature at 40°C and a wet bulb temperature at 20°C. The air leaving the spray humidifier is not saturated. Which of the following statements is true?

  1. Air gets cooled and humidified.

  2. Air gets heated and humidified.

  3. Air gets heated and dehumidified.

  4. Air gets cooled and dehumidified.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$Givan : t_{sp}=42^0C,t_{db}=40^0C,t_{wb}=20^0C \\ \text{Here we see that $t_{sp}>t_{db}$}\\ \text{Here air gets heated, Also water is added to it, so it gets humidified}$

Multiple choice

Assertion A: The amount of moisture in the atmosphere is related to the latitude. Reason R: The capacity to hold moisture in the form of water vapour is related to the temperature.

  1. Both A and R are individually true and R is the correct explanation of A.

  2. Both A and R are individually true, but R is not the correct explanation of A.

  3. A is true, but R is false.

  4. A is false, but R is true.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The amount of moisture in atmosphere is related to the latitude because the temperature depends upon the latitude, and capacity to hold moisture is related to the temperature.

Multiple choice

Choose incorrect statement.

  1. With an ascent of every 165 metres, the temperature is reduced by 10o C

  2. Capacity of air to hold moisture decreases with a rise in temperature of the air

  3. Absolute humidity is expressed in grams per cubic metre of air

  4. The air pressure decreases with decrease in temperature
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The normal lapse rate is approximately 6.5 degrees Celsius per 1000 meters, or 1 degree Celsius per 165 meters. The option states 10 degrees Celsius, which is incorrect.