How does air speed & wind effect the level of smog in a city?

Answer 1

Smog tends to linger more when the air is still, hot or cold, humid and high pressure.

The still air prevents the smog from being dispersed into the surroundigs.

Hor air can contain more water vapour which leads to increased humidity, the water vapour traps the particulate matter.

Cold conditions are more conducive to forming fog and mist and this too can trap the smoke etc, (smog comes from SMoke and fOG, smoke is the particulate matter, and the water vapour is the fog).

High pressure tends to bring settled weather and hence there's less likely to be any wind, it also means there's more pressure pushing down and keeping the smog closer to the ground.

By far the most important factor is wind, a good breeze will quickly disperse the smog but that's only going to happen when there's a difference in air pressure (air from high pressure rushes in to fill the void created by areas of low pressure, the greater the difference between high and low the greater the potential for wind).

Answer 2

Wind blows pollutants away. When there is no wind, pollutants form smog and it just sits there and builds up.

Answer 3

wind is a big air mixer. it dilutes and moves. if a certain air mass is "polluted", it will be mixed with adjacent air masses making it seem less polluted.