What high-altitude cloud observed moving in from the south often indicates an approaching warm front?

What high-altitude cloud observed moving in from the south often indicates an approaching warm front?

• A. Nimbostratus
• B. Cirrus
• C. Cumulus
• D. Stratus

Answer: (B)

Cirrus clouds are high-altitude, wispy clouds made of ice crystals. When they move in from the south, they often signal a warm front approaching because the warm air ahead of the front lifts moisture up to higher levels first, forming these thin, cirrus clouds before lower, thicker clouds arrive. They act as the first clue that weather is about to change as a warm air mass begins to advance. Lower or mid-level clouds like nimbostratus (rain-bearing and widespread), stratus (low, gray, overcast layers), or cumulus (puffy, vertical development) indicate other weather situations and usually come after or with the front rather than serving as the initial sign.

Cirrus clouds are high-altitude, wispy clouds made of ice crystals. When they move in from the south, they often signal a warm front approaching because the warm air ahead of the front lifts moisture up to higher levels first, forming these thin, cirrus clouds before lower, thicker clouds arrive. They act as the first clue that weather is about to change as a warm air mass begins to advance.

Lower or mid-level clouds like nimbostratus (rain-bearing and widespread), stratus (low, gray, overcast layers), or cumulus (puffy, vertical development) indicate other weather situations and usually come after or with the front rather than serving as the initial sign.