Why do trees have rings signifying their age?

Question

Is it like a “this is when it was really cold” or some other variable that causes the change?

In: 2

Answer 1

Pretty much, yes.

It grows fastest in the spring and summer, then slows as it dries up and then slows more as winter sets in.

Think about deciduous trees. They lose all their leaves in the winter and don’t really grow much at all.