Avielevate / DGCA CPL papers / Aviation Meteorology / ISA and Temperature
ISA and Temperature — DGCA CPL Aviation Meteorology
Chapter 01 of the Aviation Meteorology paper. 67 practice questions in the Avielevate bank, every one with its answer key, filterable into a timed set on this chapter alone.
What this chapter covers
The learning objectives we file ISA and Temperature questions under, and how many sit behind each. These come straight out of the bank and are regenerated whenever it changes — they are what is there today, not a claim.
| Learning objective | In the bank |
|---|
| 0301 The Atmosphere & ISA (Standard Atmosphere) | 38 questions |
| 0305 Temperature | 29 questions |
Sample ISA and Temperature questions, answered and explained
Real questions from this chapter, with the answer marked and the reasoning written out — the same explanations you get inside the app.
030412 · ISA and Temperature
While cruising at FL200, the outside air temperature reads -30°C. How does this compare with the ISA value at that level?
- A5°C below the ISA value
- B5°C above the ISA value
- C10°C below the ISA value
- D10°C above the ISA value
Why that is the answer
Temperature deviation from ISA is the actual temperature minus the ISA temperature at the same level. First find ISA at FL200 using surface 15°C and the 2°C per 1000 ft lapse: 15 - (2 x 20) = 15 - 40 = -25°C. The measured OAT is -30°C. Deviation equals actual minus ISA: -30 - (-25) = -5°C, i.e. 5°C colder than ISA. Option a states exactly this. Option b reverses the sign. Options c and d use 10°C, which would require ISA of -20°C or -40°C, neither of which is correct for FL200. The method is always: compute ISA at the level, then subtract it from the observed temperature. The correct answer is a.
- ISA at FL200 = 15 - (2 x 20) = -25°C
- Deviation = actual - ISA = -30 - (-25) = -5°C
- Negative deviation means colder than ISA
- Correct answer: a
030469 · ISA and Temperature
At a certain location the 300 hPa chart shows -54°C, and the significant weather chart places the tropopause at FL330. What is the most likely temperature at FL350?
- A-48°C
- B-60°C
- C-56.5°C
- D-64°C
Why that is the answer
The 300 hPa surface lies near FL300, where the temperature is -54°C. The tropopause is reported at FL330. Between FL300 and the tropopause the normal lapse of 2°C per 1000 ft still applies, so from FL300 to FL330 is 3000 ft, giving 6°C of cooling: -54 - 6 = -60°C at the tropopause FL330. Above the tropopause, in the lower stratosphere, temperature is essentially constant (isothermal), so climbing the further 2000 ft from FL330 to FL350 produces no additional cooling. The temperature at FL350 therefore remains about -60°C. Option a, -48°C, ignores cooling up to the tropopause. Option c, -56.5°C, is the ISA tropopause value and is not derived from the data. Option d, -64°C, wrongly keeps cooling above the tropopause. The correct answer is b.
- 300 hPa ~ FL300 at -54°C; tropopause at FL330
- Cool FL300 to FL330: 3000 ft x 2°C/1000 ft = 6°C, giving -60°C
- Above tropopause temperature is constant, so FL350 stays -60°C
- Correct answer: b
030627 · ISA and Temperature
Standard surface air temperature readings are taken:
- Aright at ground level
- Bat a height of roughly 10 metres above the ground
- Cat a height of about 4 feet above the ground
- Dat a height of about 4 metres above the ground
Why that is the answer
By international (WMO/ICAO) convention, surface air temperature is measured by a thermometer housed in a screen at a standard height of about 1.25 m, roughly 4 feet, above short grass. This standard height avoids the strong temperature extremes right at the ground, which can be much hotter by day and colder by night due to radiation, while still representing the air people and aircraft operate in near the surface. Option a (at ground level) would sample the radiating surface, not the air, and give unrepresentative extremes. Option b (10 metres) is the standard height for WIND, not temperature. Option d (4 metres) is too high and not the convention. The correct standard exposure height is about 4 feet above ground level, option c.
- Surface temperature uses a standard screen height
- That height is about 1.25 m, roughly 4 ft
- Ground level gives unrepresentative extremes
- 10 m is the standard height for wind, not temperature
- Answer is c, about 4 ft above ground level
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Frequently asked
How many ISA and Temperature questions are there for the DGCA CPL Aviation Meteorology paper?
Avielevate's bank carries 67 published ISA and Temperature questions for Aviation Meteorology, mapped across 2 learning objectives. Every one has its answer key, and explanations are being written across the whole bank.
How much of the Aviation Meteorology paper is ISA and Temperature?
The DGCA does not publish a per-chapter breakdown of its papers, so nobody can honestly tell you — and we will not guess. What we can tell you is what students who have just sat a paper reported meeting, which is measured rather than rumoured: that is the exam recall report inside the app.
What is the best way to revise ISA and Temperature?
Sit a short timed set on this chapter alone, tag how sure you were of each answer, then drill the two that actually leak marks: the ones you got right while guessing, and the ones you got wrong while confident. Avielevate does that tagging for you and puts anything you got wrong back in front of you on a spaced schedule.
The rest of the Aviation Meteorology paper
One account covers every chapter of every paper.
← All Aviation Meteorology chapters · All six DGCA CPL papers