Cold is transported away from the poles and moves it into the deep and eventually towards the equator. The resulting current helps to draw warmer waters from the mid-latitudes towards the poles. The overall effect is to moderate much of the worlds climate.
Hail forms when its is A. SUPER cold and B they first have to accumulate into raindrops and then freeze, so basically they water molecules are just forming into regular rain and then the temperature suddenly drops the raindrops freeze and turn into hailstones. Hope that helps!
