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Thermodynamics & Cloud Physics (Meteorology) Solved Questions & Notes (2026) - Apex Rankers

Meteorology & Atmospheric Sciences > Meteorology > Thermodynamics & Cloud Physics

35 Total Solved Questions
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Thermodynamics & Cloud Physics

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Q. 1 Meteorology
Difficulty: Easy (1 Mark)
What is the 'Dew Point Temperature' (Td)?
A
The temperature at which pure water boils at sea level
B
The temperature to which air must be cooled at constant pressure and moisture content to reach saturation (100% relative humidity)
✓ Correct
C
The temperature inside a cloud when rain starts
D
The lowest temperature recorded at night
💡 Step-by-Step Explanation & Concept Rationale
Dew point is the temperature to which an air parcel must be cooled at constant pressure and constant water vapor content for saturation to occur.
Q. 2 Meteorology
Difficulty: Easy (1 Mark)
When ambient air temperature equals the dew point temperature, what is the Relative Humidity (RH)?
A
0%
B
50%
C
100%
✓ Correct
D
Depends on altitude
💡 Step-by-Step Explanation & Concept Rationale
When actual vapor pressure equals the saturation vapor pressure (T = Td), the relative humidity is exactly 100%.
Q. 3 Meteorology
Difficulty: Medium (1 Mark)
What equation describes the exponential increase of saturation vapor pressure with temperature?
A
Navier-Stokes equation
B
Clausius-Clapeyron equation
✓ Correct
C
Bernoulli's equation
D
Hydrostatic equation
💡 Step-by-Step Explanation & Concept Rationale
The Clausius-Clapeyron equation (des/dT = L * es / (Rv * T^2)) governs the equilibrium vapor pressure over a plane surface of liquid water, showing that warm air can hold exponentially more moisture (~7% increase per 1 °C).
Q. 4 Meteorology
Difficulty: Medium (1 Mark)
What is 'Specific Humidity' defined as in atmospheric thermodynamics?
A
Ratio of mass of water vapor to the mass of dry air (mv / md)
B
Ratio of mass of water vapor to the total mass of moist air (mv / (mv + md))
✓ Correct
C
Ratio of actual vapor pressure to saturation vapor pressure
D
Mass of water vapor per unit volume of air
💡 Step-by-Step Explanation & Concept Rationale
Specific humidity (q) is the ratio of water vapor mass to the total mass of the moist air parcel (mv / m_total), typically expressed in g/kg.
Q. 5 Meteorology
Difficulty: Medium (1 Mark)
What is the 'Mixing Ratio' (w or r) in meteorology?
A
Ratio of mass of water vapor to the mass of dry air (mv / md)
✓ Correct
B
Ratio of volume of nitrogen to volume of oxygen
C
Ratio of cloud droplets to raindrops
D
Ratio of sensible heat to latent heat
💡 Step-by-Step Explanation & Concept Rationale
Mixing ratio (w) is the mass of water vapor per unit mass of dry air (mv / md), usually expressed in grams of water vapor per kilogram of dry air (g/kg).
Q. 6 Meteorology
Difficulty: Medium (1 Mark)
What is the Lifting Condensation Level (LCL)?
A
The altitude at which a rising air parcel becomes warmer than the surrounding air
B
The altitude at which an unsaturated air parcel lifted dry-adiabatically becomes saturated (RH = 100%)
✓ Correct
C
The height of the tropopause
D
The altitude where hail forms
💡 Step-by-Step Explanation & Concept Rationale
The LCL is the height at which an air parcel lifted adiabatically cools to its dew point, marking the cloud base of cumuliform clouds.
Q. 7 Meteorology
Difficulty: Hard (1 Mark)
What is the Level of Free Convection (LFC)?
A
The level at which a lifted parcel first becomes buoyant (warmer and less dense than surrounding environment)
✓ Correct
B
The surface where wind speed drops to zero
C
The top of the anvil cloud
D
The freezing level (0 °C isotherm)
💡 Step-by-Step Explanation & Concept Rationale
The LFC is the height at which a parcel lifted from the surface becomes warmer than its ambient environment, allowing it to accelerate upward freely under its own positive buoyancy.
Q. 8 Meteorology
Difficulty: Hard (1 Mark)
What is Convective Available Potential Energy (CAPE) a measure of on a thermodynamic sounding (skew-T)?
A
The kinetic energy of horizontal geostrophic winds
B
The integrated positive buoyant energy available to an air parcel between the LFC and Equilibrium Level (EL)
✓ Correct
C
The thermal conductivity of soil
D
The total solar irradiance absorbed by the ground
💡 Step-by-Step Explanation & Concept Rationale
CAPE represents the integrated amount of buoyant work done on an air parcel as it rises from the LFC to the Equilibrium Level (EL), measured in J/kg. High CAPE (> 2000 J/kg) indicates potential for severe thunderstorms.
Q. 9 Meteorology
Difficulty: Hard (1 Mark)
What is Convective Inhibition (CIN)?
A
The amount of work required to lift an air parcel from the surface to its Level of Free Convection (negative buoyancy area)
✓ Correct
B
The friction of trees on the wind
C
The rate at which rain evaporates before hitting the ground
D
The Coriolis deflection on rising thermals
💡 Step-by-Step Explanation & Concept Rationale
CIN represents the negative area on a thermodynamic diagram that an air parcel must overcome (by solar heating or mechanical lifting) to reach the LFC.
Q. 10 Meteorology
Difficulty: Easy (1 Mark)
Which cloud type is classified as a 'high cloud' composed almost exclusively of ice crystals, typically occurring above 6,000 meters (20,000 feet)?
A
Stratocumulus
B
Cirrus
✓ Correct
C
Nimbostratus
D
Altocumulus
💡 Step-by-Step Explanation & Concept Rationale
Cirrus clouds are high-altitude, detached clouds of delicate, fibrous or wispy appearance composed entirely of ice crystals.
Q. 11 Meteorology
Difficulty: Easy (1 Mark)
Which cloud is known as the thunderstorm cloud, characterized by enormous vertical development and often an anvil-shaped fibrous top?
A
Cumulonimbus (Cb)
✓ Correct
B
Nimbostratus (Ns)
C
Altostratus (As)
D
Cirrocumulus (Cc)
💡 Step-by-Step Explanation & Concept Rationale
Cumulonimbus (Cb) is a massive vertically developed cloud that produces heavy showers, thunder, lightning, squalls, and sometimes hail and tornadoes.
Q. 12 Meteorology
Difficulty: Easy (1 Mark)
What type of cloud produces steady, continuous, widespread rain or snow without thunderstorms?
A
Cumulonimbus
B
Nimbostratus
✓ Correct
C
Cirrocumulus
D
Stratocumulus
💡 Step-by-Step Explanation & Concept Rationale
Nimbostratus is a dark, thick, featureless mid-to-low level grey cloud layer that produces continuous, steady precipitation over large areas.
Q. 13 Meteorology
Difficulty: Medium (1 Mark)
What are 'Mammatus' clouds?
A
Lenticular clouds that form over mountain peaks
B
Bag-like, hanging pouch-like cloud protrusions often observed on the underside of a cumulonimbus anvil
✓ Correct
C
Thin, feathery mare's tails high in the sky
D
Noctilucent clouds in the mesosphere
💡 Step-by-Step Explanation & Concept Rationale
Mammatus clouds are hanging, pouch-like structures formed by localized downdrafts of cold, moist air sinking into drier air beneath the anvil of severe thunderstorms.
Q. 14 Meteorology
Difficulty: Medium (1 Mark)
What is the primary precipitation formation mechanism in 'cold clouds' (clouds with temperatures below 0 °C containing both supercooled liquid water and ice crystals)?
A
Collision-coalescence process
B
Bergeron-Findeisen process (ice crystal growth via vapor deposition at expense of supercooled droplets)
✓ Correct
C
Rayleigh scattering
D
Condensation on salt particles
💡 Step-by-Step Explanation & Concept Rationale
The Bergeron-Findeisen process operates because the saturation vapor pressure over ice is lower than over supercooled water at the same temperature. Water vapor deposits onto ice crystals while liquid droplets evaporate.
Q. 15 Meteorology
Difficulty: Medium (1 Mark)
What is the dominant precipitation-forming process in 'warm clouds' (temperatures everywhere above 0 °C), common in tropical maritime environments?
A
Bergeron-Findeisen process
B
Collision and coalescence
✓ Correct
C
Sublimation
D
Radiational freezing
💡 Step-by-Step Explanation & Concept Rationale
In warm clouds, larger cloud droplets fall faster than smaller ones, colliding and coalescing with them to grow into raindrops.
Q. 16 Meteorology
Difficulty: Easy (1 Mark)
What are 'Cloud Condensation Nuclei' (CCN)?
A
Large hail stones that trigger downdrafts
B
Microscopic airborne aerosol particles (like sea salt, sulfates, dust) on which water vapor condenses to form cloud droplets
✓ Correct
C
Lightning channels in the cloud
D
Molecules of nitrogen and oxygen
💡 Step-by-Step Explanation & Concept Rationale
CCN are hygroscopic aerosol particles with typical radii of 0.1 to 1 micrometer that provide surfaces for water vapor to condense upon at relative humidities close to 100%.
Q. 17 Meteorology
Difficulty: Easy (1 Mark)
What is 'supercooled water' in the atmosphere?
A
Liquid water droplets existing at temperatures below 0 °C without freezing
✓ Correct
B
Water frozen into dry ice
C
Water vapor in the mesosphere
D
Water cooled by supersonic winds
💡 Step-by-Step Explanation & Concept Rationale
Liquid water droplets in clean air can remain liquid down to -38 °C (homogeneous nucleation threshold) if ice-nucleating particles are absent. This is termed supercooled water.
Q. 18 Meteorology
Difficulty: Medium (1 Mark)
What is the phenomenon called when rain evaporates before reaching the ground, appearing as dark vertical streaks hanging beneath a cloud?
A
Graupel
B
Virga
✓ Correct
C
Rime
D
Derecho
💡 Step-by-Step Explanation & Concept Rationale
Virga refers to streaks or shafts of precipitation that fall from a cloud but evaporate or sublimate before reaching the ground, common in hot, dry environments.
Q. 19 Meteorology
Difficulty: Medium (1 Mark)
What precipitation type consists of translucent pellets of ice formed when raindrops fall through a deep freezing layer near the ground and refreeze?
A
Sleet (ice pellets)
✓ Correct
B
Freezing rain
C
Hail
D
Drizzle
💡 Step-by-Step Explanation & Concept Rationale
Sleet (ice pellets) occurs when snow melts into rain in an elevated warm layer, then refreezes into ice pellets while passing through a deep sub-freezing layer near the ground.
Q. 20 Meteorology
Difficulty: Medium (1 Mark)
How does 'Freezing Rain' differ from sleet?
A
Freezing rain falls as snow crystals
B
Freezing rain falls as supercooled liquid drops through a shallow surface sub-freezing layer and freezes instantly upon impact with cold surfaces
✓ Correct
C
Freezing rain only forms in the summer
D
Freezing rain consists of large hail stones
💡 Step-by-Step Explanation & Concept Rationale
Freezing rain occurs when liquid raindrops fall through a very shallow sub-freezing layer near the ground, remaining supercooled until striking cold ground objects, instantly forming a glaze of clear ice.
Q. 21 Meteorology
Difficulty: Medium (1 Mark)
What is 'Graupel' (soft hail or snow pellets)?
A
Large layered ice balls > 5 cm diameter
B
Opaque, white, rounded snow crystals heavily encrusted with rimed supercooled water droplets
✓ Correct
C
Frozen dew on leaves
D
Diamond dust in the polar vortex
💡 Step-by-Step Explanation & Concept Rationale
Graupel forms when supercooled cloud droplets freeze onto falling snowflakes (riming), forming small, white, fragile pellets of soft ice.
Q. 22 Meteorology
Difficulty: Medium (1 Mark)
What cloud formation is uniquely shaped like a flying saucer or lens, typically forming in the crests of mountain lee waves?
A
Altocumulus lenticularis
✓ Correct
B
Cirrostratus nebulosus
C
Cumulus humilis
D
Stratocumulus castellanus
💡 Step-by-Step Explanation & Concept Rationale
Altocumulus lenticularis (lenticular clouds) form at the crests of standing mountain gravity waves (lee waves) where moist air is forced upward, condenses, and evaporates on descending.
Q. 23 Meteorology
Difficulty: Medium (1 Mark)
What thermodynamic chart is most widely used by the Pakistan Meteorological Department (PMD) and worldwide weather services for plotting atmospheric soundings?
A
Mollweide projection
B
Skew-T ln-P diagram (or Tephigram)
✓ Correct
C
Psychrometric Mollier chart
D
Smith chart
💡 Step-by-Step Explanation & Concept Rationale
The Skew-T ln-P diagram (with temperature isotherms skewed 45° to the right and pressure on a logarithmic vertical scale) is standard in operational meteorology.
Q. 24 Meteorology
Difficulty: Easy (1 Mark)
What is 'dew point depression' on a weather sounding?
A
The difference between dry-bulb temperature and dew point temperature (T - Td)
✓ Correct
B
The drop in surface pressure as dew forms
C
The depth of water collected in a dew gauge
D
The altitude of the dew point level
💡 Step-by-Step Explanation & Concept Rationale
Dew point depression is (T - Td). A small depression (near 0) indicates near-saturation (clouds, fog), whereas a large depression indicates dry air.
Q. 25 Meteorology
Difficulty: Easy (1 Mark)
What type of fog is formed when warm, moist air moves horizontally over a colder surface (such as cold coastal water)?
A
Radiation fog
B
Advection fog
✓ Correct
C
Upslope fog
D
Steam fog (evaporation fog)
💡 Step-by-Step Explanation & Concept Rationale
Advection fog forms when warm, moist air advects horizontally over a colder surface, chilling the air below its dew point.
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