Question

Why we urine more in cold day

Answer 1

In cold weather, your body tries to keep your core warm by constricting your blood vessels and reducing the flow of blood to your skin. This process is called vasoconstriction. It is necessary because heat is lost from your skin to the environment, so your body tries to reduce the flow of blood to your extremities, especially your fingers and toes.

The constricted blood vessels cause your blood pressure to rise, because the same amount of blood has less space to flow through. To regulate your blood pressure, your kidney filters out some of the excess fluid from your blood, to reduce its volume. As your bladder fills up with the excess fluid, you feel the urge to pee. A full bladder is another way that your body loses heat, so urinating immediately helps preserve your core warmth.

Answer 2

 our body tries to keep our core warm by many methods .one such is constricting our blood vessels and reducing the  blood flow  to our skin. It is needed because heat is lost from our skin to the environment and our body tries to reduce the flow of blood to our extremities, especially our fingers and toes.
A full bladder is another way that your body loses heat, so urinating immediately helps preserve your core warmth.