Using a soft brush, lighten a portion of the sky. This bright blotch should not be completely white or completely round. The object is to make it appear as if the light is breaking through and interacting with the clouds. Using a smaller, harder brush, whiten the center of the lightened area. Do the same on the surface of the water. Be sure to measure the distance of the lightened area of the sky, and create the water highlight the same distance below the horizon. Add some happy seagulls and your done!