windpowerlib.density.temperature_gradient

windpowerlib.density.temperature_gradient(temp_air, temp_height, hub_height)[source]

Calculates the temperature at hub height using a linear temperature gradient.

A linear temperature gradient of -6.5 K/km is assumed. This function is carried out when the parameter temperature_model of an instance of the Modelchain class is ‘temperature_gradient’.

Parameters:
  • temp_air (pandas.Series or array) – Air temperature in K.
  • temp_height (float) – Height in m for which the parameter temp_air applies.
  • hub_height (float) – Hub height of wind turbine in m.
Returns:

Temperature at hub height in K.
Return type:

pandas.Series or array

Notes

The following equation is used [1]:

T_{hub}=T_{air}-0.0065\cdot\left(h_{hub}-h_{T,data}\right)

with:
T: temperature [K], h: height [m]

h_{T,data} is the height in which the temperature is measured.

Assumptions:

  • Temperature gradient of -6.5 K/km (-0.0065 K/m)

References

[1]ICAO-Standardatmosphäre (ISA). http://www.dwd.de/DE/service/lexikon/begriffe/S/Standardatmosphaere_pdf.pdf?__blob=publicationFile&v=3