References: -Air Command Weather Manual Ch 5, 11, -FTGU pages 129-132 Ground School: Meteorology 5.07 Wind References: -Air Command Weather Manual Ch 5, 11, -FTGU pages 129-132 40 Minutes

5.07 Meteorology – Wind Review from 5.06 Poll – 3 questions

Terminology and background Low level and Surface Winds Diurnal Effects 5.07 Meteorology – Wind MTPs: Terminology and background Low level and Surface Winds Diurnal Effects http://www.youtube.com/watch ?v=b43lAoovqd8

Wind the horizontal movement of air 5.07 Meteorology – Wind Wind the horizontal movement of air created by pressure differences in the horizontal

5.07 Meteorology – Pressure Gradient the rate of change of pressure over a given distance measured at right angles to the isobars close together = steeper gradient and stronger winds further apart = shallower gradient and weaker winds

5.07 Meteorology – Pressure Gradient

5.07 Meteorology – Wind Veering Wind changes direction clockwise Wind veers and increases during the day Wind veers and increases with increase in altitude Backing Wind changes direction counter-clockwise Wind backs and decreases at night Wind backs and decreases with descent in altitude

5.07 Meteorology – Pressure Gradient Example: Winds start the day at 300o and by 1400 the winds are 340o and by night they are 310o

5.07 Meteorology – Coriolis Force Earth turns below atmosphere In N Hemisphere deflected to the right To left in S Hemisphere http://www.youtube.com/watch?v=_36MiCUS1ro

5.07 Meteorology – Confirmation Questions: Wind is: The horizontal movement of air created by pressure differences (horizontal) Pressure Gradient is: The rate of change of pressure measured over a given distance, measured at right angles to the isobars Backing is: Change in direction anti-clockwise Describe Coriolis Force Rotation of earth causes air to be deflected to the right in the N Hem. Until parallel with the isobars

5.07 Meteorology – Surface Friction Friction between surface and atmosphere slows movement of air, this in turn slows Coriolis force Only up to a few thousand feet (except in mountainous regions)

Gusts a brief rapid increase of wind speed. 5.07 Meteorology – Gusts Gusts a brief rapid increase of wind speed. may be associated with a rapid change in wind direction Causes may be related to mechanical turbulence and unequal heating

5.07 Meteorology – Confirmation What is surface friction and what are it’s effects? Friction between surface and atmosphere Slows movement of air and therefore Coriolis force Air tends to move across isobars at slight angles Gusty conditions may be caused by Mechanical turbulence Uneven heating of the earth

5.07 Meteorology – Diurnal Effects If isobaric pattern and pressure gradient are identical During day… At night…

5.07 Meteorology – Diurnal Effects Land and Sea Breezes

5.07 Meteorology – Diurnal Effects

5.07 Meteorology – Diurnal Effects

5.07 Meteorology – Diurnal Effects Memory Tool Ana goes up and throws the Kat down.

5.07 Meteorology – Diurnal Effects

BC Online Ground School 5.07 Meteorology – Diurnal Effects

When do sea breezes occur? What causes a Katabatic wind? 5.07 Meteorology – Review When do sea breezes occur? During the day – high pressure over water, low over land. What causes a Katabatic wind? At night, air in contact with slope cools, becomes more dense, and flows down hill. What is it called when vapour changes to liquid? Condensation

5.07 Meteorology – Review Effects of a Hurricane