**Notation**

**c**_{o}(z) _{ }**= **Orography factor

**I**_{v}(z) _{ }**= **Turbulence intensity

**k**_{l } _{ }**= **Turbulence factor

**k**_{r } _{ }**= **Terrain factor depending on the roughness length

**v**_{b }**= **Basic wind velocity

**v**_{m}(z)_{ }**= **The mean wind velocity

**z**_{min} _{ }**= **Minimum height

**z**_{o } _{ }**= **Roughness length

**σ**_{v } _{ }**= **Standard deviation of the turbulence

The turbulence intensity *I*_{v}(z) at height z is defined as the standard deviation of the turbulence divided by the mean wind velocity. The turbulence intensity *I*_{v}(z) is calculated using equation below.

The standard deviation of the turbulence *σ*_{v} is calculated using equation below.

Terrain factor *k*_{r} and basic wind velocity, *v*_{b} are defined in the *Mean Wind* title.

Turbulence factor *k*_{l} may be given in the National Annex. The recommended value for *k*_{l} is 1,0.

Orography factor *c*_{o}(z) is defined by user.

Roughness length *z*_{o} is given in EN 1991-1-4 Table 4.1.