Condensation & Clouds: Understanding Water's Transformation

[EEristavi]

I understand that condensation occurs when water (in gas form) looses energy and becomes liquid. What I don't understand why some surface is needed to form a liquid water

 

[.Scott]

I understand that condensation occurs when water (in gas form) looses energy and becomes liquid. What I don't understand why some surface is needed to form a liquid water

Here is a wiki article on the phenomenon:
https://en.wikipedia.org/wiki/Cloud_condensation_nuclei
Water can condense without a surface - but the water must be chilled well below freezing before that will happen.

I am not sure if the exact mechanism for this is described, but I would point out that without a surface, most water particles that collide with each other will be at a temperature above the ambient - simply because of the speed of the collision. Then, both the heat of the collision and the latent heat of condensation would need to be somehow surrendered to the environment.

 

[sophiecentaur]

Water can condense without a surface - but the water must be chilled well below freezing before that will happen.

What happens at the spout of a boiling kettle?

 

[.Scott]

What happens at the spout of a boiling kettle?

According to the wiki article, there needs to be particulates or freezing temperatures.
The wiki article cites the following, which is basically college text.
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter5/ccn.html

 

[anorlunda]

What happens at the spout of a boiling kettle?

Leave it to an Englishman to focus on a boiling kettle. I love those powerful electric tea kettles you have there.

 

[sophiecentaur]

I love those powerful electric tea kettles

The water needs to nearly boiling when it first comes into contact with the tea. Everywhere else in the World they pour luke warm water - or even dip the tea bag into a cup of water that was heated way back at the bar or in the kitchen. You've no idea, you guys. But you put whisky into ice, too!

According to the wiki article,

I scanned through it but couldn't actually find that statement and I also looked at the other article. We all know that you can form fog and mist without the temperature being very low so they must be looking deeper and considering large droplet formation. It'll be the temperature that determines whether large enough drops can form to cause rain, probably because there will be an equilibrium when the evaporation rate is the same as the condensation rate.

 

[Lord Jestocost]

I understand that condensation occurs when water (in gas form) looses energy and becomes liquid. What I don't understand why some surface is needed to form a liquid water

To understand, read about „Nucleation“: https://en.wikipedia.org/wiki/Classical_nucleation_theory

 

[.Scott]

I scanned through it but couldn't actually find that statement and I also looked at the other article.

From the first paragraph of the wiki article:

In the atmosphere, this surface presents itself as tiny solid or liquid particles called CCNs. When no CCNs are present, water vapour can be supercooled at about −13°C (8°F) for 5–6 hours before droplets spontaneously form (this is the basis of the cloud chamber for detecting subatomic particles).

We all know that you can form fog and mist without the temperature being very low so they must be looking deeper and considering large droplet formation. It'll be the temperature that determines whether large enough drops can form to cause rain, probably because there will be an equilibrium when the evaporation rate is the same as the condensation rate.

At low altitudes and certainly indoors at a residence, there are always lots of airborne particles.
The second article I cited (the college Meteorology text) also notes that very humid conditions are unusual in polluted urban areas - because there are so many seeds available in the air.

 

[davenn]

Water can condense without a surface - but the water must be chilled well below freezing before that will happen.

From the first paragraph of the wiki article:

it doesn't say must be super cooled

In the atmosphere, this surface presents itself as tiny solid or liquid particles called CCNs. When no CCNs are present, water vapour can be supercooled at about −13°C (8°F) for 5–6 hours before droplets spontaneously form (this is the basis of the cloud chamber for detecting subatomic particles).

"can be cooled ... before" big differencethis is all related to dew point
https://en.wikipedia.org/wiki/Dew_point