A process plant produces spherical pollutant particles, and a system needs to be designed to prevent them escaping the plant perimeter. The settling velocity of the particles is a critical factor in the design of the system.

The local climate is such that the air is warmer and more humid in summer cooler and drier $($less humid$)$ in winter.

Will the particle settling velocity be higher, lower or the same in winter compared to the settling velocity in summer?

Also give explaantion using bluff object concept