WIND ENERGY SYSTEMS - Cd3wd

Chapter 2—Wind Characteristics 2–6
Low
u
❅■
❅
f p ✛
.
✲
f g
✲ f c
Figure 3: Wind forces in a low-pressure area
High
❅ ❅❘
u
f c
✛
.
✲
f p
✲ f g
Figure 4: Wind forces in a high-pressure area
wind” applies only to a wind flowing in the vicinity of nearly straight isobars.
For the high pressure area of Fig. 4, the pressure and Coriolis forces reverse in direction.
The pressure gradient force for an anticyclone is therefore
f p = f c − f g (8)
The difference between Eqs. 7 and 8 means that cyclones and anticyclones tend to stabilize
at somewhat different relative pressures and wind speeds. Since the atmosphere is never
completely stable, these differences are not usually of major concern.
Wind Energy Systems by Dr. Gary L. Johnson November 20, 2001