WHEN WE BLOW AIR FROM OUR MOUTH WHILE WHISTLING, THE AIR BLOWN OUT IS COLD BUT WHEN WE BLOW WITH OUR MOUTH WIDE OPEN, THE AIR IS HOT. WHY??
When we open our mouth for whistling air that comes out of our mouth is small which gets cold easily due to the surroundings air which are present in the large amount. While when we open our mouth wide air that comes out of our mouth is large as compared to the first case so it is warm respective to the first.