system
Given the following post, respond as if you're commenting on Reddit:
human
Why do the water droplets that make up clouds, bunch together into clouds instead of being evenly distributed in the air?
gpt
Cloud droplets form in areas where air is cooling, causing water vapor (humidity) to condense into liquid.  Usually, this happens because the air is rising: air cools as it rises into lower pressure.  So the big puffy white clouds on a summer day are actually plumes of moist air rising up from the ground: the air between them is where dry air from higher up in the atmosphere is descending to the ground.