When seeking thermals, which observational cue can help locate them besides cloud formation?

• A. Converging streams of dust or smoke
• B. Loud engine noise
• C. Smell of rain
• D. Bright sunlight intensity

Answer: (A)

Thermals are rising columns of warm air formed when the sun heats the ground, and gliders climb best where these updrafts are strongest. An observational cue that helps locate them without relying on clouds is watching how dust or smoke behaves near the ground. When a thermal is active, dust or smoke tends to be drawn toward a vertical updraft, creating converging streams toward a single point. That convergence shows you where the lift is centered and where you should turn to stay inside the thermal.

The other options don’t reliably indicate lift. Engine noise just points to aircraft nearby, not the presence of rising air. The smell of rain isn’t connected to thermals. Bright sunlight can increase thermal formation, but it doesn’t itself reveal where lift is occurring.