How might differences in climate (dry or humid, hot or cold) ...

[abarnes]

How might differences in climate (dry or humid,
  hot or cold) affect the possibility of harvesting
  water from the atmosphere? What will be an ideal response?

Question 2

Why is it so expensive to desalinate water? What will be an ideal response?

[Tabitha_2016]

Answer to Question 1

Answers will vary. It may be easier to harvest water in
humid climates, where the air contains a lot of available
moisture. Cold climates could also support atmospheric
water harvesting because of condensation, but cold air
holds very little water vapor.

Answer to Question 2

Because of the amount of power used in pumping and
filtering saltwater.