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DEPUTY DIRECTOR / SENIOR METEOROLOGIST (BS-18) Complete Preparation Guide & Solved Questions (2026) - Apex Rankers

FPSC Recruitment Examination Syllabus & Question Bank

3156 Total Solved Questions
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Meteorology

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Q. 1 Meteorology
Difficulty: Medium (1 Mark)
According to Wien's Displacement Law, what is the relationship between the temperature of a blackbody and the wavelength of maximum emission?
A
Wavelength is directly proportional to temperature
B
Wavelength is inversely proportional to absolute temperature
✓ Correct
C
Wavelength is proportional to the fourth power of temperature
D
Wavelength is independent of temperature
💡 Step-by-Step Explanation & Concept Rationale
Wien's Displacement Law states that lambda_max = b / T, where the wavelength of maximum emission is inversely proportional to the absolute temperature (Kelvin) of the emitting body.
Q. 2 Meteorology
Difficulty: Easy (1 Mark)
The Stefan-Boltzmann Law states that the total radiant energy emitted per unit area of a blackbody is proportional to which power of its absolute temperature?
A
First power (T)
B
Second power (T^2)
C
Third power (T^3)
D
Fourth power (T^4)
✓ Correct
💡 Step-by-Step Explanation & Concept Rationale
The Stefan-Boltzmann Law is given by E = sigma * T^4, meaning the total emissive power of a blackbody is directly proportional to the fourth power of its absolute temperature.
Q. 3 Meteorology
Difficulty: Medium (1 Mark)
What is the approximate solar constant (total solar irradiance received at the top of Earth's atmosphere on a surface normal to the rays at mean Earth-Sun distance)?
A
342 W/m²
B
980 W/m²
C
1361 to 1367 W/m²
✓ Correct
D
2400 W/m²
💡 Step-by-Step Explanation & Concept Rationale
The solar constant is approximately 1361–1367 W/m² (often approximated as 1367 W/m² or ~2 cal/cm²/min).
Q. 4 Meteorology
Difficulty: Easy (1 Mark)
What is the global average planetary albedo of Earth (the fraction of incoming solar radiation reflected back to space)?
A
Approximately 10%
B
Approximately 30%
✓ Correct
C
Approximately 50%
D
Approximately 70%
💡 Step-by-Step Explanation & Concept Rationale
Earth's planetary albedo is roughly 0.30 (or 30%), primarily reflected by clouds (~20%), atmospheric backscattering (~6%), and the surface (~4%).
Q. 5 Meteorology
Difficulty: Easy (1 Mark)
Which surface typically has the highest albedo for solar radiation?
A
Dark ocean water at high sun angle
B
Freshly fallen snow
✓ Correct
C
Dense conifer forest
D
Moist black soil
💡 Step-by-Step Explanation & Concept Rationale
Fresh snow has one of the highest albedos in nature, reflecting 80% to 90% (0.80–0.90) of incident solar radiation.
Q. 6 Meteorology
Difficulty: Medium (1 Mark)
In atmospheric physics, what is the 'atmospheric window'?
A
The layer in the stratosphere where ozone absorbs harmful UV rays
B
The wavelength band between roughly 8 and 12 micrometers where terrestrial infrared radiation escapes relatively unabsorbed by water vapor and CO2
✓ Correct
C
The hole in the polar vortex over Antarctica
D
The visible spectrum region between 0.4 and 0.7 micrometers
💡 Step-by-Step Explanation & Concept Rationale
The atmospheric window lies in the thermal infrared region (8–12 micrometers, excluding the 9.6 micrometer ozone band), where greenhouse gases absorb relatively little, allowing heat to escape directly to space.
Q. 7 Meteorology
Difficulty: Easy (1 Mark)
What is the value of the Dry Adiabatic Lapse Rate (DALR) in Earth's atmosphere?
A
6.5 °C per kilometer
B
9.8 °C per kilometer (~1 °C / 100 m)
✓ Correct
C
3.2 °C per kilometer
D
12.5 °C per kilometer
💡 Step-by-Step Explanation & Concept Rationale
The Dry Adiabatic Lapse Rate (DALR = g / Cp) is approximately 9.8 °C/km (or ~1 °C per 100 meters), representing the rate of cooling of an unsaturated parcel of air as it ascends adiabatically.
Q. 8 Meteorology
Difficulty: Medium (1 Mark)
Why is the Saturated (or Moist) Adiabatic Lapse Rate (SALR) always less than the Dry Adiabatic Lapse Rate (DALR)?
A
Moist air has higher molecular weight than dry air
B
Condensation releases latent heat of vaporization, which partially offsets adiabatic cooling
✓ Correct
C
Water droplets absorb solar radiation directly
D
Frictional dissipation warms the rising saturated parcel
💡 Step-by-Step Explanation & Concept Rationale
As a saturated air parcel rises and cools, water vapor condenses into liquid droplets. This phase change releases latent heat of vaporization into the parcel, reducing its net cooling rate to ~4 to 7 °C/km.
Q. 9 Meteorology
Difficulty: Easy (1 Mark)
What is the standard average Environmental Lapse Rate (ELR) in the International Standard Atmosphere (ISA) troposphere?
A
9.8 °C/km
B
6.5 °C/km
✓ Correct
C
4.0 °C/km
D
1.5 °C/km
💡 Step-by-Step Explanation & Concept Rationale
The standard atmosphere assumes a constant tropospheric environmental lapse rate of 6.5 °C per 1,000 meters (or 1.98 °C per 1,000 feet) up to 11 km.
Q. 10 Meteorology
Difficulty: Medium (1 Mark)
Under what condition is an atmospheric layer considered 'absolutely stable'?
A
When Environmental Lapse Rate (ELR) > Dry Adiabatic Lapse Rate (DALR)
B
When Environmental Lapse Rate (ELR) < Saturated Adiabatic Lapse Rate (SALR)
✓ Correct
C
When SALR < ELR < DALR
D
When ELR is equal to DALR
💡 Step-by-Step Explanation & Concept Rationale
When the ELR is less than the SALR, an air parcel will always be cooler (and denser) than the surrounding ambient air whether it is dry or saturated, suppressing vertical motion.
Q. 11 Meteorology
Difficulty: Medium (1 Mark)
Under what condition is an atmospheric layer said to exhibit 'conditional instability'?
A
When ELR < SALR
B
When ELR > DALR
C
When SALR < ELR < DALR
✓ Correct
D
When ELR = 0 (isothermal)
💡 Step-by-Step Explanation & Concept Rationale
Conditional instability occurs when the ELR lies between SALR and DALR. The layer is stable for unsaturated air parcels but unstable if the parcel becomes saturated.
Q. 12 Meteorology
Difficulty: Easy (1 Mark)
What is a 'temperature inversion' in meteorology?
A
A layer where temperature decreases rapidly with height
B
A layer where atmospheric temperature increases with increasing altitude
✓ Correct
C
A phenomenon where ground temperature drops below freezing
D
A seasonal reversal of wind directions
💡 Step-by-Step Explanation & Concept Rationale
A temperature inversion is a deviation from the normal decrease of temperature with altitude, where temperature increases with height. Inversions act as lids, suppressing convection and trapping pollutants.
Q. 13 Meteorology
Difficulty: Medium (1 Mark)
Which type of temperature inversion typically forms on calm, clear winter nights over land surfaces such as the plains of Punjab?
A
Frontal inversion
B
Subsidence inversion
C
Radiation (or ground) inversion
✓ Correct
D
Turbulence inversion
💡 Step-by-Step Explanation & Concept Rationale
Radiation inversions develop on clear, calm nights when the ground loses heat rapidly via longwave terrestrial radiation, cooling the air in contact with the ground faster than the air above.
Q. 14 Meteorology
Difficulty: Medium (1 Mark)
A 'subsidence inversion' is typically associated with which synoptic weather feature?
A
Deep tropical depression
B
Anticyclone (high-pressure system) where sinking air warms adiabatically
✓ Correct
C
Fast-moving cold front
D
Intense convective thunderstorm
💡 Step-by-Step Explanation & Concept Rationale
Subsidence inversions occur within high-pressure systems (anticyclones) where large-scale sinking air warms adiabatically, becoming warmer than the marine or surface boundary layer beneath it.
Q. 15 Meteorology
Difficulty: Hard (1 Mark)
What is 'potential temperature' (theta) in dynamic meteorology?
A
The temperature an air parcel would attain if brought adiabatically to a standard reference pressure of 1000 hPa
✓ Correct
B
The highest temperature recorded during the day
C
The dew point temperature converted into Kelvin
D
The virtual temperature at sea level
💡 Step-by-Step Explanation & Concept Rationale
Potential temperature (theta) is defined as theta = T * (P0 / P)^(R / Cp), which is the temperature a parcel would have if compressed or expanded adiabatically to reference pressure P0 = 1000 hPa.
Q. 16 Meteorology
Difficulty: Hard (1 Mark)
If potential temperature (theta) increases with height (d theta / dz > 0), what is the static stability of the dry atmosphere?
A
Statically unstable
B
Statically neutral
C
Statically stable
✓ Correct
D
Super-adiabatic
💡 Step-by-Step Explanation & Concept Rationale
When d theta / dz > 0, the dry atmosphere is statically stable. When d theta / dz = 0, it is neutral; when d theta / dz < 0, it is statically unstable (super-adiabatic).
Q. 17 Meteorology
Difficulty: Hard (1 Mark)
What is the Brunt-Vaisala frequency (N) a measure of in atmospheric physics?
A
The rotational speed of a tornado vortex
B
The frequency at which a vertically displaced parcel oscillates in a stably stratified fluid
✓ Correct
C
The radar pulse repetition frequency
D
The rate of lightning strikes per minute
💡 Step-by-Step Explanation & Concept Rationale
The Brunt-Vaisala frequency N = sqrt((g / theta) * (d theta / dz)) is the buoyancy frequency at which an air parcel oscillates vertically when disturbed in a stably stratified atmosphere.
Q. 18 Meteorology
Difficulty: Hard (1 Mark)
What is 'virtual temperature' (Tv) in atmospheric thermodynamics?
A
The temperature simulated by numerical weather models
B
The temperature that dry air must have in order to have the same density as moist air at the same pressure
✓ Correct
C
The temperature measured by satellite radiometers
D
The temperature of the wet-bulb thermometer
💡 Step-by-Step Explanation & Concept Rationale
Because moist air is less dense than dry air at the same temperature and pressure, virtual temperature (Tv) is the theoretical temperature dry air would have to match the moist air's density: Tv approx T * (1 + 0.61 * q).
Q. 19 Meteorology
Difficulty: Medium (1 Mark)
What is the primary mechanism of heat transfer from the Earth's surface into the lowest few millimeters of the atmosphere?
A
Convection
B
Molecular conduction
✓ Correct
C
Advection
D
Condensation
💡 Step-by-Step Explanation & Concept Rationale
In the laminar boundary layer (first millimeter above surface), heat is transferred by molecular conduction. Above this thin layer, turbulent eddy diffusion and convection dominate.
Q. 20 Meteorology
Difficulty: Medium (1 Mark)
Which gas is the most potent contributor to Earth's natural greenhouse effect in terms of total percentage absorption?
A
Carbon dioxide (CO2)
B
Methane (CH4)
C
Water vapor (H2O)
✓ Correct
D
Ozone (O3)
💡 Step-by-Step Explanation & Concept Rationale
Water vapor is by far the single largest natural greenhouse gas contributor, accounting for roughly 60% of Earth's natural greenhouse warming (80-85% including clouds).
Q. 21 Meteorology
Difficulty: Easy (1 Mark)
Why is the sky blue during midday under clear skies?
A
Due to absorption of red wavelengths by ozone
B
Due to Rayleigh scattering by gas molecules, which is inversely proportional to the 4th power of wavelength (1/lambda^4)
✓ Correct
C
Due to Mie scattering by cloud water droplets
D
Due to reflection of ocean waters
💡 Step-by-Step Explanation & Concept Rationale
Rayleigh scattering by atmospheric molecules (N2, O2) scatters shorter wavelengths (blue/violet) far more effectively than longer wavelengths (red) because scattering intensity is proportional to 1/lambda^4.
Q. 22 Meteorology
Difficulty: Easy (1 Mark)
Why do sunrises and sunsets appear distinctly red or orange?
A
Solar radiation shifts to microwave frequencies
B
The solar beam traverses a much longer atmospheric optical path (air mass), scattering out blue/violet light and leaving red/orange to penetrate
✓ Correct
C
The sun cools significantly at horizon level
D
The Doppler effect shifts the solar spectrum
💡 Step-by-Step Explanation & Concept Rationale
At low sun angles, sunlight passes through a path length up to 10-30 times greater than at zenith. Rayleigh scattering removes the blue and green light along the path, allowing the longer orange and red wavelengths to reach the observer.
Q. 23 Meteorology
Difficulty: Medium (1 Mark)
What optical scattering regime applies when particulate diameter is comparable to or larger than the wavelength of light, such as in clouds and fog?
A
Rayleigh scattering
B
Raman scattering
C
Mie scattering
✓ Correct
D
Compton scattering
💡 Step-by-Step Explanation & Concept Rationale
Mie scattering occurs when particles (cloud droplets, pollen, smoke) have sizes comparable to or larger than the wavelength of light. It is nearly independent of wavelength, making clouds and fog appear white.
Q. 24 Meteorology
Difficulty: Medium (1 Mark)
A 22-degree halo around the Sun or Moon is produced by light refraction through which atmospheric particles?
A
Spherical water droplets in altostratus clouds
B
Hexagonal ice crystals in cirrostratus clouds
✓ Correct
C
Volcanic sulfate aerosols in the stratosphere
D
Sand particles in dust storms
💡 Step-by-Step Explanation & Concept Rationale
Halos of 22° radius are produced by refraction of light through randomly oriented hexagonal column ice crystals present in high-altitude cirrostratus clouds.
Q. 25 Meteorology
Difficulty: Easy (1 Mark)
What atmospheric optical phenomenon creates a primary rainbow?
A
Diffraction of light through fog droplets
B
One internal reflection and two refractions of sunlight within spherical raindrops
✓ Correct
C
Two internal reflections within ice prisms
D
Scattering by nitrogen molecules
💡 Step-by-Step Explanation & Concept Rationale
A primary rainbow is formed when sunlight enters a spherical raindrop, undergoes refraction, reflects once off the back of the drop, and refracts again as it exits (angular radius ~42°).
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