2-D RIDGE

wind speed: Normal
Kzt = (1 + K₁K₂K₃)² Speed-up Zone K₁ = 0.36 x (Upwind) x (Downwind) H Lh H/Lh ≥ 0.2 Upper 1/2 2-D RIDGE

2-D Ridge Characteristics (K₁ = 0.36):

Concentrated Flow: Wind cannot flow around the sides - all airflow must go over the ridge

Higher Speed-up Effects: Creates intense acceleration zones as flow is forced upward

Vertical Updraft: Strong vertical flow patterns over the ridge crest

Sharp Transitions: Rapid changes in wind speed and direction

Topographic Factor Requirements:

Structure: Must be in upper half of hill/ridge

H/Lh ≥ 0.2: Height to length ratio requirement

Height: H ≥ 15 ft (Exposure C,D) or 60 ft (Exposure B)

Isolation: No similar upwind obstructions within 100H or 2 miles

Formula: Kzt = (1 + K₁K₂K₃)² where K₁ = shape factor, K₂ = distance factor, K₃ = height factor