2
votes
1answer
273 views

How much water is destroyed in photosynthesis, relative to the world's supply?

Water is involved in the photosynthesis. How much water are we talking about compared with the total amount on water on Earth? Is it enough to have an effect on the average age of water molecules?
7
votes
2answers
4k views

How cold does it need to be for spit to freeze before hitting the ground?

What is the dominant form of heat transfer between warm water and cold air? If a $100 mg$ drop of water falls through $-40 C$ air, how quickly could it freeze? Is it credible that in very cold ...