Wilson effect (astronomy)
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In astronomy, the Wilson effect is the perceived depression of a sunspot's umbra, or center, in the Sun's photosphere. The magnitude of the depression for the umbra is between 500 and 1000 km, with an
Wilson's original sketch demonstrating the Wilson effect.
Convection
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Convection is the transfer of heat through the physical movement of fluids, where warmer, less-dense material rises and cooler, denser material sinks.
Thermal image of a newly lit Ghillie kettle. The plume of hot air resulting from the convection current is visible.
Painting of William Prout
Fireplace, with grate and chimney
This color schlieren image reveals thermal convection originating from heat conduction from a human hand (in silhouette) to the surrounding still atmosphere, initially by diffusion from the hand to the surrounding air, and subsequently also as advection as the heat causes the air to start to move upwards.