In fine weather the early morning is often dead calm, but heating of the upper and lower layers of air as the day progresses causes a mixing of these layers, bringing down to the ground some of the more swiftly moving air from above. For surfers, this often means the best surf of the day is at dawn when the wind is still very light.

The fact that land warms up more quickly than the ocean is also a factor for the surfer to take into account - this causes the effect we know as a "sea breeze". Sea breezes are only felt a short way inland, hence the name. As the land warms up in the morning, so does the layer of air above it. Fluids (yes, air is a fluid) always flow from high to low pressure (ie. the "easy route"). Therefore the heating of the land in the morning causes an off-shore breeze. (The air flowing from the warmer high pressure area over the land to the cooler low pressure area over the ocean). . Another good reason to get up for a "dawny"!