Dew, Frost and Fog

1. Dew, Frost and Fog

2. Dew • Condensation on surface when temperature falls to the dew point temperature • Often occurs on cold, clear nights in areas open to the sky? • Why surface emits infrared radiation to space, cooling surface • Dew forms when temperature drops to the dew point

6. Dew • Often associated with periods when high pressure (a.k.a., an anticyclone) is positioned overhead • Highs are associated with clear skies and calm or weak winds. • Why are weak winds good for dew? Less mixing of warmer air from above!

8. Car’s in the open can get covered with dewCars in a carport gather little dewWhy?

9. Dew Protection: Roof Lessens Infrared Cooling to Space

10. More Dew Facts • More dew after a moist period or in moist areas. Higher dew point! • Dew releases latent heat of condensation and reduces temperature drops after it starts to form

11. Frost

14. FOG

15. Radiation Fog

16. Ground Fog

19. Advection Fog

24. Upslope Fog

28. Steam Fog

32. FRONTAL FOG

33. Average Number of Days with Dense Fog

34. Foggiest Place in U.S.: Cape Disappointment