You will have less lung capacity as your lungs get cooled down. You're breathing through your mouth and not your nose, which doesn't give enough time to warm up the air inside your head before the air reaches your lungs.

It's best to breath through your nose when possible, as this allows the air to warm up and be moisturized before reaching your lungs as your lungs do have an optimal operating temperature. But I'm sure we all know your nose doesn't allow proper breathing when doing sports.