|
|
What happens inside a cloud?
Micro-scale Processes - Cloud Droplet Formation
Intuitively, you might guess that cloud droplets form when the air temperature
cools to its
dew point temperature.
This is a good estimation, but only because the atmosphere is dirty.
On an ordinary day, a volume of air the size of your index finger contains between 1,000 and 150,000 particles. In order for water vapor to condense and form liquid water in clean air, the relative humidity needs to be a few hundred percent. So, how do cloud droplets form?
Particles, called condensation nuclei, provide a surface for water vapor to condense onto. Condensation nuclei decrease the surface tension of the droplets. Sources of condensation nuclei include volcanoes, forest fires, pollution, sea salt, and sulfate particles emittedby phytoplankton, in the oceans.
With condensation nuclei present, cloud droplets can form at approximately 100% relative humidity.
Next page -> Micro-scale processes - cloud droplet formation continued
Links and resources
Micro-scale Processes - Cloud Droplet Formation
Intuitively, you might guess that cloud droplets form when the air temperature
cools to its
dew point temperature.
This is a good estimation, but only because the atmosphere is dirty.On an ordinary day, a volume of air the size of your index finger contains between 1,000 and 150,000 particles. In order for water vapor to condense and form liquid water in clean air, the relative humidity needs to be a few hundred percent. So, how do cloud droplets form?
Particles, called condensation nuclei, provide a surface for water vapor to condense onto. Condensation nuclei decrease the surface tension of the droplets. Sources of condensation nuclei include volcanoes, forest fires, pollution, sea salt, and sulfate particles emittedby phytoplankton, in the oceans.
With condensation nuclei present, cloud droplets can form at approximately 100% relative humidity.
Next page -> Micro-scale processes - cloud droplet formation continued
Links and resources
