Importance of difference between SVP over ice and water?

[JesseC]

SVP = saturated vapour pressure.

I understand that the SVP over ice is less than that over water for temperatures less than 0C. I'm doing an exam question which asks 'what is the significance of this difference?'. My first guess is that in clouds with both ice and water present, this difference results in growth of ice crystals at the expense of droplets. Not sure if this is the only significance, and whether anyone could point me to some others.

 

[Andre]

Check the Bergeron process. Precipitation will form much easier with the ice crystals growing continuously than miniscule water droplets coalescing via collisions.

Also, -not sure- it may the reason why the moist adiabat is not as as constant as the dry adiabat. If vapor condenses to water the released latent heat is about 2.5 kJ/g, but when it sublimates to ice crystals it's 2.833 kJ/g, adding another variable.

http://www.usatoday.com/weather/wlatent.htm