Meteorology: 7 Latest ATPL Questions Explained | Clouds and Fog

Clouds and fog are easy to recognise in theory, but ATPL questions often test the small details: what triggered the cloud, what limits its development, how fog forms, and why reported surface visibility may differ from what you actually see on approach.

In this walkthrough, we break down seven recently reported questions from 05004 – Clouds and Fog, covering cloud identification, sea smoke, frontal and radiation fog, METAR interpretation, haze, and slant visibility.

This article is the text-based version of our recent video session, created for students who prefer reading or want a quick reference for revision. Prefer to video learning? Follow the complete video walkthrough: 7 Latest ATPL Meteorology Questions, where ATPL pilot Michal explains every question step by step.

Watch the full walkthrough:  

Watch full Meteorology walkthrough sessions on our YouTube channel and boost your exam confidence. 

7 Latest ATPL Meteorology Questions | Clouds and Fog

• AIR-275987: Recognising Nimbostratus

• AIR-247299: Identifying Cloud Type, Trigger and Limiting Factors

• AIR-246598: Formation and Effects of Sea Smoke

• AIR-247030: Frontal Fog and Conditions Leading to Dissipation

• AIR-246545: Fog Depth and Visibility in the METAR 

• AIR-245567: Estimating Runway Threshold Visibility in Haze

• AIR-247222: Slant Visibility During an Approach

Meteorology: 7 Latest ATPL Questions Explained. Continue practising recently reported Meteorology questions across a broader range of syllabus topics.

Question 1: Recognising Nimbostratus

Question ID AIR-275987: Which cloud type (genus) is described by the following definition? Grey cloud layer, often dark, the appearance of which is rendered diffuse by more or less continuously falling rain or snow, which in most cases reaches the ground. It is thick enough throughout to blot out the sun. Low, ragged clouds frequently occur below the layer, with which they may or may not merge.

1. Nimbostratus

2. Altostratus

3. Stratus

4. Stratocumulus

Correct Answer: Nimbostratus (Ns)

Explanation

The biggest clue is the continuous precipitation. Nimbostratus is a widespread, thick cloud layer associated with prolonged rain or snow that often reaches the ground. The cloud can become dense enough to completely obscure the Sun, while lower fragments of cloud may also form beneath the main layer.

A useful memory aid comes from the name itself: “nimbo” refers to precipitation.

Other layered clouds can look similar. Altostratus, for example, often forms a grey or bluish sheet covering much of the sky, but it is not defined by the persistent precipitation described in this question.

Stratocumulus, meanwhile, is generally more broken or cellular in appearance rather than forming one thick precipitation-producing layer.

Exam Tip

Do not choose a cloud simply because it is grey or covers most of the sky. Focus on the type and duration of precipitation.

If the description gives you: Thick layer + Sun obscured + prolonged rain or snow → Nimbostratus. 

Your Sky Guide: 10 Cloud Types to Know. Sharpen your cloud recognition skills with ten cloud types every ATPL student should know, including their formation, appearance, and associated weather.

Question 2: Identifying Cloud Type, Trigger and Limiting Factors

Question ID AIR-247299: Please refer to the annex. The cloud in the image is a (1) _______, which is formed by (2) _______ and triggered by (3) _______. The vertical growth of the cloud is restricted by (4) _______.

• 1) Cumulus; (2) convection; (3) heating from below; (4) a subsidence inversion

• (1) Cumulus; (2) advection; (3) turbulence; (4) a sea breeze inversion

• (1) Cumulonimbus capillatus; (2) advection; (3) heating from below; (4) the tropopause

• (1) Altocumulus castellanus; (2) convection; (3) orographic lifting; (4) a subsidence inversion

Correct Answer: 1) Cumulus; (2) convection; (3) heating from below; (4) a subsidence inversion

Explanation

The cloud shown is a cumulus cloud: an individual, well-defined cloud with a relatively flat base and vertical development above it.

Cumulus clouds form when air is forced to rise and cool until it becomes saturated. One of the most common triggers is heating from below. The ground warms the air immediately above it, producing rising thermals and therefore convection.

Convergence and orographic lifting can also trigger rising motion, but the key process associated with typical cumulus development is convection. Their vertical growth can be restricted by a subsidence inversion. Once the rising air reaches a stable layer where temperature increases with height, further ascent is suppressed and the cloud may spread horizontally rather than continuing to build vertically.

Exam Tip

Keep the movements of air separate:

• Convection = vertical movement;

• Advection = horizontal movement.

For cumulus, think: Heating → rising air → convection → cloud

And if the question asks what stops further growth, look for a stable layer or inversion.

Jet Streams Explained: Types, Charts & ATPL Exam Traps. Ready to move beyond Clouds and Fog? Review jet stream types, chart interpretation, clear-air turbulence, and the common traps that appear in ATPL Meteorology questions.

Question 3: Formation and Effects of Sea Smoke

Question ID AIR-246598: Sea smoke may drift onto land and affect coastal aerodromes. It forms when...

1. relatively warm and moist air moves over water with a surface temperature that is below the dew point of the moving air.

2. saturated air from the surface of the sea is forced to rise as it meets coastal cliffs, forming fog that drifts inland.

3. sea spray from breaking waves in strong surface winds forms a mist that drifts across the surface.

4. evaporated vapour from a warm water surface condenses on contact with much colder air, and is unable to rise because of a surface inversion.

Correct Answer: evaporated vapour from a warm water surface condenses on contact with much colder air, and is unable to rise because of a surface inversion.

Explanation

Sea smoke (also known as steam fog or arctic smoke), is easiest to understand by thinking about a hot drink outside on a cold winter day. 

Warm water continuously supplies moisture to the air immediately above it. When much colder air moves across the surface, this added water vapour rapidly condenses, creating a shallow fog that appears to “steam” from the water. The fog normally remains close to the surface and can form over seas, lakes and other relatively warm bodies of water before drifting towards nearby coastal aerodromes.

A useful comparison is advection fog, which forms in almost the opposite situation: relatively warm, moist air moves horizontally across a colder surface and is cooled to saturation.

Exam Tip

Remember the contrast:

Sea smoke → Cold air over warm water

Advection fog → Warm moist air over cold surface

If you can visualise steam rising from a hot cup in cold air, sea smoke becomes very difficult to forget.

Decoding the Sky: Weather Hazards & Decision Traps. Go beyond definitions and look at how poor visibility, cloud, changing weather and other hazards affect real pilot decision-making

Question 4: Frontal Fog and Conditions Leading to Dissipation

Question ID AIR-247030: If frontal fog is reported at a European aerodrome, what conditions are likely to cause the fog to dissipate?

1. The Sun will heat the surface in the cloudless skies immediately after the warm front has passed and clear the fog.

2. After the front has passed there is no more cold air to cool the humid air close to the surface, the visibility should slowly improve

3. The descending air in the warm sector will cause fog droplets to fall on the surface as dew, the visibility should improve

4. The wind backs as the front passes, the air becomes drier and fog particles are re-absorbed into water vapour

Correct Answer: After the front has passed there is no more cold air to cool the humid air close to the surface, the visibility should slowly improve

Explanation

Frontal fog develops in association with a front, commonly when precipitation and moist air interact with colder air near the surface. Around a warm front, for example, relatively warm precipitation can fall into colder air below. Evaporation adds moisture to this lower layer and may eventually bring it to saturation, producing fog.

The important point for the exam is that the fog is linked to the frontal environment itself. Once the front passes, the temperature and moisture structure near the surface changes. The supply of cold air and moisture that supported the fog is removed or weakened, allowing visibility to improve and the fog to dissipate.

Exam Tip

The clue is in the name: Frontal fog moves with  and depends on  the front. If the front passes and the supporting conditions disappear, expect the fog to clear.

Aviation Weather: Fronts, Clouds and Flight Conditions. Want to connect the theory? See how warm and cold fronts influence cloud formation, precipitation, visibility, and the conditions you can expect in flight.

Question 5: Fog Depth and Visibility in the METAR

Question ID AIR-246545: Shortly after dawn, an inland aerodrome (Eindhoven,The Netherlands) reports the following METAR: EHEH 010610Z 33005KT 0300 R21/0450 FG NSC 06/06 Q1018=

This means that the aerodrome is experiencing (1).....,which probably extends from the surface to (2).......

• (1) radiation fog (2) less than 300 feet

• (1) frontal fog (2) less than 300 feet

• (1) radiation fog (2) 1000 feet or more

• (1) frontal fog (2) 1000 feet or more

Correct Answer: (1) radiation fog (2) less than 300 feet

Explanation

Several clues in the METAR point towards radiation fog. The conditions at the aerodrome are: very light wind and no significant cloud (NSC). The air temperature is the same as dew point 06/06 (which means 100 % relative humidity). Fog is reported.

The observation is made shortly after dawn. Radiation fog normally develops overnight when the ground loses heat through terrestrial radiation. The air immediately above the surface cools with it, eventually reaching saturation.

The wind is light, around 3–5 kt is particularly favourable. Some movement is needed to mix the cooled air through a shallow layer, but stronger winds would disperse the fog.

Finally, the sky is essentially clear. This matters because cloud cover reduces nocturnal cooling by absorbing and re-radiating energy back towards the ground.

Radiation fog is therefore typically: Inland + overnight/early morning + clear sky + light wind

It is often relatively shallow and tends to dissipate after sunrise as solar heating warms the surface, usually within the first few hours of the morning.

Exam Tip

Look for the classic combination: Clear night + light wind + early morning = Radiation fog

No wind at all is not necessarily ideal. A small amount of mixing helps create a deeper fog layer.

Master the METAR: Your Key to Aviation Weather Code. Build confidence reading METARs and learn to quickly recognise visibility, cloud, fog, temperature/dew point, and other weather information you’ll see in the exam.

Question 6: Estimating Runway Threshold Visibility in Haze

Question ID AIR-245567: The report for a Spanish aerodrome in September an hour before sunset is as follows:

METAR LEXX 211730Z 26008KT 220V320 3000 HZ SKC Q1010.

At what distance would a pilot expect to see the threshold of runway 26 from the direction of approach?

1. More than 3000 m.

2. 3000 m.

3. More than 1000 m but less than 1500 m.

4. More than 1500 m but less than 3000 m.

Correct Answer: More than 1500 m but less than 3000 m.

Explanation

The important distinction here is between reported surface visibility and slant visibility.

A METAR visibility of 3,000 m describes predominantly horizontal visibility measured near the surface. An approaching pilot, however, is looking downwards through the haze towards the runway. This is slant visibility, and in haze, mist or fog it may be significantly worse than the reported horizontal visibility.

So the runway threshold should become visible at less than the reported 3,000 m.

The question then gives you another clue: no RVR is included in the report. In the exam logic used here, RVR would be reported once visibility becomes sufficiently poor around the runway, so its absence indicates that conditions have not fallen into the lower visibility range represented by the alternative answer. This leaves the expected threshold visibility somewhere between roughly 1,500 m and 3,000 m.

Exam Tip

• Do not assume: METAR visibility = distance you will see the runway from the air.

• In haze, mist and fog: Slant visibility < surface visibility.

Fog Alert: 6 Types Every Pilot Should Know. Review the main types of fog, how they form, and why reduced visibility matters for flight planning and airport operations.

Question 7: Slant Visibility During an Approach

Question ID AIR-247222: Surface visibility at your destination in the centre of France in August is reported as 1500 metres in haze, with an inversion at 500 feet above aerodrome level and sky clear above. When making a non-precision approach to runway 18 shortly before sunset with a minimum descent altitude of 600 feet above aerodrome level, at what range would you expect to see the runway and why?

1. Less than 1500 metres because the Sun in the pilot's eyes will reduce the ability to distinguish objects and therefore air-to-ground visibility.

2. Less than 1500 metres because the sunlight reflecting from the haze particles will reduce flight visibility.

3. More than 1500 metres because the aircraft will still be flying above the haze.

4. Less than 1500 metres because the sunlight reflecting from the top of the haze layer will reduce air-to-ground visibility.

Correct Answer: Less than 1500 metres because the sunlight reflecting from the top of the haze layer will reduce air-to-ground visibility.

Explanation

This question develops the same principle as the previous one, but adds an inversion layer.

Haze consists largely of particles suspended in the atmosphere. An inversion produces a stable layer that restricts vertical mixing, allowing those particles to remain trapped below it.

In this case, the inversion lies at 500 ft above the aerodrome, while the aircraft reaches an MDA of 600 ft. The aircraft is therefore initially above the top of the haze layer and looking down through it towards the runway.

The reported 1,500 m surface visibility represents horizontal visibility within the layer. The pilot's actual view towards the runway is along a sloping line through the haze, so the air-to-ground or slant visibility will be worse.

The low Sun angle shortly before sunset can make this even more noticeable. Light reflecting and scattering from the top of the haze layer reduces contrast between the runway and its surroundings.

As a result, the runway may not become visible until the aircraft is closer than the reported 1,500 m surface visibility.

Exam Tip

When you see: Haze + inversion + aircraft above the layer think about slant visibility, not simply the METAR visibility.

The reported surface visibility tells you what can be seen horizontally near the ground. It does not necessarily tell you how far a pilot can see down through the layer on approach.

Next Step

If you understand why the weather behaves the way it does, the correct answer often stands out. With consistent study and plenty of question practice, the logic starts to click. Once it does, Meteorology becomes far more manageable.

Want to test the theory while it’s fresh? Practise more questions from 05004 – Clouds and Fog in the Airhead ATPL Question Bank and see how these concepts appear in real exam-style scenarios.