Water Droplet Coalescence

{
  "id": "MLC-T-ENV-030047",
  "term": "Water Droplet Coalescence",
  "field": "Environment",
  "definition": "1. The process by which water droplets in a cloud collide and come together to form raindrops.\n\n2. When the upward motions of air are more vigorous, the cloud particles can grow much more rapidly. When they exceed a certain size (about 10-15 microns), their falling motions relative to the air and to each other (since different sized particles fall at different rates) causes collisions to occur. At smaller sizes, the particles cannot push through the air between them so collisions are prevented by this air \"cushion\". The collision rate of the larger particles depends on how many particles there are and how fast they fall, which depends on how large the particles are. If the colliding particles stick together to form an even larger particle, the rate of such collisional growth increases very rapidly, despite the fact that the number of particles available decreases. Very quickly, the balance in the cloud is between growth by collisions (called coalescence) and removal of particles by sedimentation.",
  "references": [
    "NOAA National Weather Service Glossary",
    "NASA International Satellite Cloud Climatology Project Cloud Analysis - Part 8: Cloud Microphysics at http://isccp.giss.nasa.gov/climanal8.html"
  ],
  "url": "https://mlchart.com/terminology/environment/water-droplet-coalescence/"
}