Reasons For Ice Ages

Question 1

How does ice form?

Answer 1

A colder climate means precipitation falls as snow
A shorter summer means less time for melting
Snow accumulates and compression squeezes air out of lower layers - now called firn or neve
Meltwater seeps through air spaces and refreezes
As ice develops it becomes denser

Question 2

What are the climatic influences that contribute to an ice age?

Answer 2

Orbit and tilt changes
Sunspot activity - changing amounts of solar radiation received on earth
Changing amounts of volcanic dust
Increase in amount of CO2 in oceans - less in atmosphere so cooling effect
Variations in ocean currents