Which is a rising column of air that produces lift on a glider?

Which is a rising column of air that produces lift on a glider?

• A. Thermal
• B. Updraft
• C. Downdraft
• D. Convection

Answer: (A)

A thermal is a rising column of warm air that provides lift for a glider. When the ground heats up, the air near the surface becomes buoyant and starts to rise in a localized updraft. As a glider circles in the core of this rising air, it gains altitude because the buoyant air reduces the required wing lift for the same weight, allowing the glider to climb without propulsion. An updraft is a general term for upward air motion, but not every updraft forms a defined buoyant column that pilots ride for sustained lift. A downdraft is airflow moving downward, which would reduce lift. Convection is the broader heat-transfer process that can create updrafts but isn’t itself the specific lift-producing column gliders use. So the rising column of warm air that lifts a glider is a thermal.

A thermal is a rising column of warm air that provides lift for a glider. When the ground heats up, the air near the surface becomes buoyant and starts to rise in a localized updraft. As a glider circles in the core of this rising air, it gains altitude because the buoyant air reduces the required wing lift for the same weight, allowing the glider to climb without propulsion. An updraft is a general term for upward air motion, but not every updraft forms a defined buoyant column that pilots ride for sustained lift. A downdraft is airflow moving downward, which would reduce lift. Convection is the broader heat-transfer process that can create updrafts but isn’t itself the specific lift-producing column gliders use. So the rising column of warm air that lifts a glider is a thermal.