As air rises it expands and cools. Cooler air cannot hold as much water as warmer air, so as the air rises the water will condense and form clouds. This is why an area of low pressure will often be accompanied by clouds and rain

Confused. Why cant cooler air hold as much water? Above it says the air expands as it moves up, so there must be less pressure and hence due to expansion the air molecules must be further away from each other and hence more space to hold water in that was previously not there when when the air was more contracted/under higher pressure?

Help?