1. Land-Sea Breezes
Figure 6.19

2. Land-Sea Breezes

3. Mountain-Valley breezes
Figure 6.20

4. Chinook, Foehn, & Santa Ana Winds
Winds that flow down the lee side of mountain ranges

5. Hierarchy of Wind Systems
Global
ITCZ, Westerlies, and Rossby Waves
Last decades to centuries
Synoptic
Cyclones and Anticyclones, Troughs and Ridges, Pressure cells
Last days to weeks
Mesoscale
Local winds
Last hours
Microscale
Dust devils
Last minutes

6. Kinematics
September 5, 2007

7. Kinematics Means “to move” in Greek
Describes the motion of objects without considering the masses or forces that bring about that motion
Studies how the positions of things change over time, measured in coordinates

8. Atmospheric Pressure and Motion
Differences in heating cause differences in air density, which cause atmospheric motion
In the midlatitudes, the surface air temperature is due more to air movement more than radiation received
Motion is a result of atmospheric pressure differences

9. Geostrophic Wind
Winds in the upper atmosphere that flow parallel to isobars
In the Northern Hemisphere, geostrophic wind flows with low pressure to its left and high pressure to its right

10. Geostrophic Wind

11. Gradient Wind
A wind that blows at a constant speed parallel to curved isobars above the level of frictional influence is a gradient wind
An object accelerates when there is a change in its speed or direction or both
Therefore the gradient wind blowing around low-pressure is constantly accelerating because its constantly changing direction – centripetal acceleration

12. Gradient Wind

13. Gradient Wind

14. Eddies
When the wind encounters a solid object, a whirl of air – or eddy – forms on the object’s downwind side
The size and shape of the eddy depends on the size and shape of the obstacle
On a windy night, these produce tiny swirls of air that act as pulses of compressed air that reach you eardrum and produce a howling sound

15. Turbulence
Eddies that form close to mountains and beneath wave crests produce rotors
Rotors have violent vertical motion that produce extreme turbulence

16. Turbulence
Sudden changes in wind speed or direction (or both) abruptly produce wind shear
Any irregular or disturbed flow in the atmosphere that produces gusts and eddies - Turbulence

17. Turbulent eddies are common near the jet stream, where large wind speed shears exist

18. Microburst A localized column of sinking air
Once it hits the ground, it spreads quickly in all directions
Produces divergent winds at the surface
Damage similar to that of tornadoes
Tornadoes spiral inwards, microbursts spiral outwards
Particularly troublesome for landing aircraft

20. Clouds: The Basics