Which statement is true about thermals?

Which statement is true about thermals?

• A. Thermals always produce zero sink
• B. Strong thermals have proportionately greater lift than sink between them
• C. Thermals are unpredictable and have no consistent pattern
• D. Strong thermals have proportionately increased sink in the air between them

Answer: (D)

Thermals are rising air columns with sinking air in the surrounding gaps. When a thermal is strong, the updraft is vigorous, and the circulation pulls more air from the surroundings to feed that updraft. That stronger circulation also drives a stronger downward flow between the cores, so the air between thermals sinks more as the thermals get stronger. In other words, the amount of sink in the inter-thermal air increases in proportion to the strength of the thermals. This pattern explains why you see distinct, buoyant cores separated by sinking air, and why stronger thermals come with more pronounced sinking between them. The other statements fail because there is always some sink between thermals, thermals aren’t completely patternless, and the idea that lift outpaces the accompanying sink isn’t the standard relationship observed.

Thermals are rising air columns with sinking air in the surrounding gaps. When a thermal is strong, the updraft is vigorous, and the circulation pulls more air from the surroundings to feed that updraft. That stronger circulation also drives a stronger downward flow between the cores, so the air between thermals sinks more as the thermals get stronger. In other words, the amount of sink in the inter-thermal air increases in proportion to the strength of the thermals. This pattern explains why you see distinct, buoyant cores separated by sinking air, and why stronger thermals come with more pronounced sinking between them. The other statements fail because there is always some sink between thermals, thermals aren’t completely patternless, and the idea that lift outpaces the accompanying sink isn’t the standard relationship observed.