Final answer:
The development of thermals is primarily dependent on solar heating. Thermals arise due to the convection of warm air that moves upwards as the sun heats the Earth's surface.
Step-by-step explanation:
The development of thermals depends upon solar heating. Thermals are columns of rising air in the lower altitudes of Earth's atmosphere, created by uneven heating of the Earth's surface from solar radiation. This process does not necessarily require a counterclockwise circulation of air or temperature inversions; instead, it is driven by the convection of warmer air that rises upwards from the heated ground.
When the sun heats the Earth's surface, the ground becomes warmer than the surrounding air, and the warm air rises due to its lower density compared to the cooler air. This upward movement of air is essential for thermal development. It is a primary method of heat transfer in the atmosphere, along with conduction and radiation.