Avielevate / DGCA CPL papers / Aviation Meteorology
DGCA CPL Aviation Meteorology — question bank and syllabus
The atmosphere you work in: ISA and temperature, pressure and altimetry, humidity and stability, winds, clouds, thunderstorms, fog and visibility, air masses and fronts, and reading the actual reports.
What is in this paper
Every chapter we cover for Aviation Meteorology, with how many questions sit behind each one.
These counts come straight out of the question bank and are regenerated whenever it changes —
they are not a claim, they are what is there today.
Sample questions, answered and explained
A few real questions from this paper, with the answer marked and the reasoning
written out — the same explanations you get inside the app. Everything else is behind a free
account.
0310021 · ATMOSPHERE
Where are noctilucent clouds found?
- AThermosphere
- BMesosphere
- CStratosphere
Why that is the answer
**Concept**
Almost all cloud is in the troposphere. **Noctilucent clouds** (night-shining clouds) are the highest clouds of all, far above any weather.
**Explanation**
They form near the top of the **mesosphere**, at about **80 to 85 km**, close to the mesopause. Look at the diagram: this is the coldest part of the whole atmosphere, about −90 to −100°C or even colder in summer over high latitudes. There is almost no water vapour at that height, but the extreme cold is enough for tiny ice crystals to form, probably on specks of meteor dust.
They are so high that they are still lit by the sun long after sunset, when the ground and all lower clouds are in darkness. That is why they are seen glowing silvery-blue against the night sky, usually in summer at latitudes of about 50 to 70°. Look at the photo.
**Applying it to the question**
Noctilucent clouds are found in the **Mesosphere**. They should not be confused with nacreous (mother-of-pearl) clouds, which form lower, in the stratosphere at about 15 to 25 km.
**Remember for DGCA:** noctilucent = mesosphere, about 80 to 85 km; nacreous = stratosphere, about 15 to 25 km.
Image credit: okruz (public domain), via Wikimedia Commons.
0310024 · ATMOSPHERE
The stratosphere extends from the tropopause up to about:
- A50 km
- B60 km
- C40 km
Why that is the answer
**Concept**
The atmosphere is divided into layers by how the temperature changes with height. The **stratosphere** is the second layer, above the troposphere.
**Explanation**
Look at the diagram. The stratosphere begins at the **tropopause** (about 8 km over the poles, 11 km on average, 16 to 18 km over the equator). In its lower part the temperature stays nearly constant; higher up it **rises** with height, because ozone absorbs the sun's ultraviolet radiation and warms the air.
The warming continues up to the **stratopause** at about **50 km**, where the temperature reaches close to 0°C. Above it, in the mesosphere, there is too little ozone to heat the air, so the temperature starts to fall again. The change from rising to falling temperature marks the top of the stratosphere.
**Applying it to the question**
The stratosphere extends from the tropopause up to about **50 km**. The mesosphere then continues to about 80 to 85 km.
**Remember for DGCA:** tropopause about 11 km, stratopause about 50 km, mesopause about 80 to 85 km.
0310029 · ATMOSPHERE
Which middle layer of the atmosphere has a temperature inversion and is stable?
- ATroposphere
- BTropopause
- CStratosphere
Why that is the answer
**Concept**
An **inversion** is a layer in which the temperature **rises** with height instead of falling. Air in an inversion is very **stable**: a parcel pushed upwards cools as it rises, ends up colder and denser than the warmer air around it, and sinks back.
**Explanation**
Look at the diagram. Going up from the surface:
- In the **troposphere** the temperature falls with height, so air can rise and overturn, producing convection, cloud and weather.
- The **tropopause** is only the boundary between the layers, where the fall of temperature stops.
- In the **stratosphere** the temperature first stays steady and then rises with height up to about 50 km, because ozone absorbs the sun's ultraviolet radiation. This makes the stratosphere one large inversion, so it is stable, with very little vertical movement, cloud or turbulence.
In the four-layer picture (troposphere, stratosphere, mesosphere, thermosphere), the stratosphere is one of the two middle layers.
**Applying it to the question**
The layer with a temperature inversion that is stable is the **Stratosphere**. Its stability is why thunderstorm tops stop and spread out into an anvil when they reach it.
**Remember for DGCA:** stratosphere = isothermal then inversion = stable; the ozone layer is the cause of the warming.
0311008 · ATMOSPHERIC PRESSURE
Which type of inversion forms when a stable layer lies over a high-pressure area?
- ANegative
- BRadiation
- CSubsidence
- DAir mass
Why that is the answer
**Concept**
Normally the air gets colder as you go up. An **inversion** is a layer in which the temperature **rises** with height. Warm air sitting on top of cooler air is very stable, so an inversion acts like a lid on vertical movement.
**Explanation**
In a high-pressure area (anticyclone), air converges at high levels and slowly **sinks** over a wide area. This sinking is called **subsidence**. As the air descends, it moves into higher pressure and is **compressed**, so it warms at the dry adiabatic rate (about 3°C per 1,000 ft). It also becomes drier, which is why highs have little cloud.
The sinking air cannot reach the ground: near the surface it spreads out sideways. So the warmed, subsided air ends up lying on top of a cooler, unaffected surface layer. Where the two meet, the temperature increases with height: a **subsidence inversion**, typically a few thousand feet up. Look at the diagram (right half).
Below this lid, smoke, dust and moisture are trapped, which is why highs often bring **haze and poor visibility**, and sometimes a sheet of stratocumulus under the inversion.
**Applying it to the question**
A stable inversion layer formed over a high-pressure area by sinking, compressed air is a **Subsidence** inversion. A radiation inversion, by contrast, forms at ground level on clear nights as the ground cools, and it disappears after sunrise.
**Remember for DGCA:** high pressure = subsidence = warming by compression = subsidence inversion aloft, with haze trapped below.
Free while we are testing
Avielevate is in an open testing period — nobody is being charged. Create an account, fill in
the short form on the pricing page, and we switch on three months of full access: the whole
bank, timed mock exams, explanations and weak-topic analytics.
Avielevate is a preparation tool. Always study alongside the official DGCA
publications and the approved reference material for your course.
The other DGCA CPL papers
All six papers live in one workspace — one account covers whichever you are sitting.