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CSIR-UGC NET Atmospheric Science & Agrometeorology: practice questions

CSIR-UGC NET — Earth, Atmospheric, Ocean and Planetary Sciences · India · National Testing Agency for CSIR

Original practice questions written to the published syllabus · not past papers
9worked here, free
23written to this exam in this subject
7syllabus units

What this subject covers

Radiation, heat, moisture and motion in the atmosphere, and how weather and climate are measured and used on farms. ICAR AICE subject 60 Agricultural Meteorology examines it in depth.

In the exams: ICAR AICE-JRF/SRF subject 60 (whole paper); ICAR AIEEA-PG 3.1 Agricultural Meteorology; GATE ES Section 6 (meteorology for dispersion)

What CSIR-UGC NET asks from it

CSIR-UGC NET — Earth, Atmospheric, Ocean and Planetary Sciences

Atmospheric thermodynamics, radiation, general circulation, monsoon and tropical cyclones, cloud physics and precipitation processes.

Where the 23 questions fall

How our questions for CSIR-UGC NET spread across the units of Atmospheric Science & Agrometeorology. Difficulty: 3 easy, 17 medium, 3 hard.

Radiation laws: Planck, Stefan-Boltzmann, Wien, Kirchhoff, Beer-Lambert5
Atmospheric stability and adiabatic processes5
Layers of the atmosphere and their characteristics4
Pressure systems, winds and general circulation4
Clouds, precipitation processes and forms2
Monsoons, air masses, fronts and cyclones2
Weather forecasting for agriculture and agromet advisories1

9 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · Layers of the atmosphere and their characteristics · easy

What is the average environmental lapse rate in the troposphere?

  1. About 15 °C per km
  2. About 1 °C per km
  3. About 6.5 °C per km
  4. About 9.8 °C per km
Answer and working

C. About 6.5 °C per km

The standard atmosphere uses 6.5 °C per km. 9.8 °C per km is the dry adiabatic lapse rate of a rising unsaturated parcel, not the average environmental profile.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

2 · Layers of the atmosphere and their characteristics · medium

Why is the tropopause higher over the equator than over the poles?

  1. The Earth's rotation flings the stratosphere outward at the equator, thinning the troposphere there
  2. Gravity is stronger at the equator, compressing the troposphere into a thinner, higher layer
  3. Ozone is concentrated over the equator, which pushes the stratosphere down to about 8 km
  4. Strong surface heating and deep convection in the tropics lift the troposphere to about 16–18 km
Answer and working

D. Strong surface heating and deep convection in the tropics lift the troposphere to about 16–18 km

Vigorous tropical convection mixes heat high, giving a tropopause near 16–18 km versus about 8 km at the poles. Rotation, ozone placement and gravity are not the explanation; gravity is in fact slightly weaker at the equator.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

3 · Radiation laws: Planck, Stefan-Boltzmann, Wien, Kirchhoff, Beer-Lambert · medium

A leaf surface at 300 K has an emissivity of 0.95. Using σ = 5.67 × 10⁻⁸ W m⁻² K⁻⁴, how much longwave radiation does it emit?

  1. 436 W m⁻²
  2. 0.029 W m⁻²
  3. 459 W m⁻²
  4. 1.45 W m⁻²
Answer and working

A. 436 W m⁻²

E = εσT⁴ = 0.95 × 5.67 × 10⁻⁸ × 300⁴ = 436 W m⁻². 459 ignores emissivity; using T³ gives 1.45; using 27 °C instead of kelvin gives a negligible value.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

4 · Radiation laws: Planck, Stefan-Boltzmann, Wien, Kirchhoff, Beer-Lambert · medium

Kirchhoff's law states that, for a body in thermal equilibrium,

  1. its transmitted radiation falls exponentially with the depth of the medium
  2. its wavelength of peak emission is inversely proportional to its temperature
  3. its emissivity at a wavelength equals its absorptivity at that wavelength
  4. its emission is proportional to the fourth power of its absolute temperature
Answer and working

C. its emissivity at a wavelength equals its absorptivity at that wavelength

Kirchhoff's law links emissivity and absorptivity at the same wavelength. The other statements are the Stefan–Boltzmann law, Wien's law and the Beer–Lambert law.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

5 · Radiation laws: Planck, Stefan-Boltzmann, Wien, Kirchhoff, Beer-Lambert · medium

A solar beam strikes level ground at 60° from the vertical. Compared with a beam at normal incidence, the energy received per unit area is

  1. unchanged, because the beam intensity is the same
  2. twice as much, by the inverse-square law
  3. half, by Lambert's cosine law
  4. a quarter, by the Stefan–Boltzmann law
Answer and working

C. half, by Lambert's cosine law

Irradiance ∝ cos(zenith angle); cos 60° = 0.5. The inverse-square law concerns distance from the source, and Stefan–Boltzmann concerns emission, not incidence angle.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

6 · Atmospheric stability and adiabatic processes · medium

Surface air temperature is 30 °C and the dew point is 18 °C. Using the approximation of 125 m per °C of dew-point depression, at what height will a rising parcel reach its lifting condensation level?

  1. 12 m
  2. 2250 m
  3. 3750 m
  4. 1500 m
Answer and working

D. 1500 m

LCL ≈ 125 × (30 − 18) = 1500 m. 3750 m uses the air temperature alone; 2250 m uses the dew point alone; 12 m forgets the 125 m factor.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

7 · Pressure systems, winds and general circulation · medium

Using f = 2Ω sin φ with Ω = 7.292 × 10⁻⁵ s⁻¹, what is the Coriolis parameter at 30° latitude?

  1. 7.292 × 10⁻⁵ s⁻¹
  2. 3.646 × 10⁻⁵ s⁻¹
  3. 1.458 × 10⁻⁴ s⁻¹
  4. 0 s⁻¹
Answer and working

A. 7.292 × 10⁻⁵ s⁻¹

f = 2 × 7.292 × 10⁻⁵ × sin 30° = 2 × 7.292 × 10⁻⁵ × 0.5 = 7.29 × 10⁻⁵ s⁻¹. 1.46 × 10⁻⁴ is the polar value; 3.65 × 10⁻⁵ omits the factor 2; 0 is the equatorial value.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

8 · Pressure systems, winds and general circulation · medium

Why do surface winds blow across isobars towards low pressure rather than parallel to them?

  1. Surface air is heavier, so gravity pulls it downhill into low pressure regardless of other forces
  2. Isobars are drawn only for the upper atmosphere, so surface winds ignore pressure patterns
  3. Friction slows the wind and weakens the Coriolis force, so the pressure gradient force wins partly
  4. The Coriolis force is strongest at the surface and pushes air directly into low-pressure centres
Answer and working

C. Friction slows the wind and weakens the Coriolis force, so the pressure gradient force wins partly

Above the friction layer the wind is near-geostrophic, parallel to isobars. Near the ground friction reduces speed and thus Coriolis deflection, so air crosses isobars towards low pressure. Coriolis is not strongest at the surface, and surface charts do show isobars.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

9 · Monsoons, air masses, fronts and cyclones · medium

A sequence of cirrus, cirrostratus, altostratus and then nimbostratus with prolonged light rain typically signals the approach of

  1. a warm front
  2. a sea-breeze front
  3. a subtropical high
  4. a cold front
Answer and working

A. a warm front

Warm air rising gently over cold air ahead of a warm front gives a broad, lowering cloud sequence with prolonged rain. Cold fronts give a narrow band of cumulonimbus and showers; highs give clear skies.

Further reading: See the manual sources: FAO-56, WMO Guide to Agricultural Meteorological Practices, and the textbooks named there

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Atmospheric Science & AgrometeorologyThe full study manual, free CSIR-UGC NETFormat, sections and how it has changed

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