Identify the sequence of clouds in the sky (first to last) as a warm front approaches an observer/place in the middle latitudes.

A. Cirrostratus
B. Nimbostratus
C. Altostratus
D. Cirrus

Choose the correct answer from the options given below:

Correct option is A

As a warm front approaches, clouds form in a predictable sequence due to the gradual lifting of warm, moist air over a colder air mass. The correct order of cloud development is:

1. Cirrus (D) – The first clouds observed are high-altitude, wispy cirrus clouds, which indicate an approaching warm front.
2. Cirrostratus (A) – These thin, ice-crystal clouds cover the sky in a veil, often causing a halo effect around the sun or moon.
3. Altostratus (C) – These mid-level clouds thicken, covering more of the sky and causing diffuse sunlight.
4. Nimbostratus (B) – The final stage before precipitation, these thick, low clouds produce steady, widespread rain or snow.

Thus, the correct sequence is Cirrus → Cirrostratus → Altostratus → Nimbostratus (D → A → C → B).

Information Booster:

• Warm fronts are gradual transitions between warm and cold air masses, bringing steady precipitation and cloud thickening over time.
• Cirrus clouds appear first due to moisture spreading at high altitudes.
• Cirrostratus clouds create a halo effect, indicating increasing humidity.
• Altostratus clouds obscure the sun and signal imminent rain.
• Nimbostratus clouds bring steady rain or snow, marking the full arrival of the warm front.