Slide 1

Understanding Local Diurnal Winds Sea Breezes and Land Breezes dependent on the differences in heating and cooling between land and water. Upslope and downslope winds forced by the differences in heating and cooling between terrain and lowlands. Slide 2 Sea and Land Breezes Slide 3 Sea Breeze Return Flow Slide 4 Land Breeze Circulation Slide 5 Sea Breeze Facts Builds up in coastal regions during the day Best developed in late spring and summer when sun is strongest. Can cool the coast by 5-15F, sometimes more. Tends to suppress clouds over water, but enhance over land. Starts at the coast and extends landward and seeward, 20-50 km Slide 6 Sea Breeze Front: sharp leading edge of cooler air Slide 7 Can See the Influence of Sea and Land Breezes on Clouds Slide 8 Washington Coast Sea Breeze Front Slide 9 Slide 10 Slide 11 Slide 12 Colliding Sea Breezes Can Produce Strong Upward Motion Slide 13 Slide 14 Fig. 7-7, p. 176 Slide 15 Sea Breeze Winds Along the Southern Oregon Coast Gusts frequently reach 30-35 knots during the summer during the afternoon. Very painful to stay on the beach! Strong pressure gradient normal to the coast between the warm land areas and the cold upwelling water. Slide 16 2-minute average July-August winds along the Northwest coast. Slide 17 Southern Oregon Coast Near Brookings Slide 18 Summer Diurnal Winds Slide 19 The Sound Breeze Viewed Using Ferry Data Slide 20 Picture take in Sequim looking N Strong Regional Sea Breeze Winds During the Summer Slide 21 Land Breezes Tend to Be Weak in the Northwest Why? Because the land rarely cools down more than the water. Local minimum temperatures generally in the low to mid-50ssimilar to the temperature of the Sound and the Pacific Ocean. But it can happen in winter during unusually cold periods. Slide 22 Land Breeze example during a cold period. Slide 23 Slope Winds Slide 24 Slope Winds Upslope Flow on Heated Slopes Downslope Flow on Cooled Slopes Slide 25 Slide 26 Low temperatures are generally cooler in low spots on cold, cloud-free nights. Slide 27 Eastern Washington Slope flows Slide 28 Fig. 7-11, p. 178 Slide 29 Warm LL Valley breeze Cool H H Mountain breeze Editable Text Slide 30 Fig. 7-12, p. 179