Question 1 Report
A glider pilot looks for a 'thermal' to gain height without a motor. A thermal is
A thermal is a rising column of warm, less dense air (a convection current). Ground warmed by the Sun heats the air above it, which expands, becomes less dense and rises as a column, and a glider circling in it is carried upward. It is not a conduction current or a downward flow of cold air, and it is a movement of air, not a beam of radiation.
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