What is the natural phenomenon that moves the
cough droplets through the air?

For a mild human cough in air at 20 °C and 50% relative humidity, we found that ... larger droplets are dispersed into smaller ones gradually while moving away from the ... Complex phase change and transport phenomena such as evaporation and ... Natural Ventilation for Infection Control in Health-Care Settings

Explanation

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).