Option 1: Slow ascent of air - slow condensation - heavy downpour. This option suggests that when air slowly rises, condensation occurs and results in a heavy downpour. However, this is not entirely accurate. While slow ascent of air can lead to condensation, it does not necessarily guarantee a heavy downpour. The intensity of the downpour is dependent on various factors such as the amount of moisture present in the air and atmospheric conditions.

Option 2: Rapid ascent of air - large raindrops, heavy downpour. This option correctly states that when air rapidly ascends, it leads to the formation of large raindrops and results in a heavy downpour. This is known as convective precipitation, where warm moist air rises rapidly, cools, and condenses into raindrops.

Option 3: Pressure decreased, air compressed - heavy downpour. This option is incorrect. Decreased pressure and compressed air do not directly cause a heavy downpour. Changes in pressure and compression are related to atmospheric circulations but do not determine the intensity or occurrence of rainfall.

Option 4: Descent of air - air warmed - heavy downpour. This option is also incorrect. The descent of air typically leads to warming, but this does not necessarily result in a