In Ashes, the Wind direction is calculated with respect to the North, which is indicated by the N letter in the north arrow glyph on the upper right corner of the Simulation window (shown in the picture below)
This means that when the wind angle is 0, the wind comes from the north. When opening a default template in Ashes, the wind angle is 0 and the turbine is oriented so that the rotor is facing North, i.e. facing the wind, as shown in the image below:
In this figure, the wind direction is represented by the white arrow, while the yellow plane is perpendicular to the wind direction.
A positive angle will rotate the wind towards East, i.e. clockwise when the model is seen from above. The figure below illustrates a wind angle of 45 degrees, corresponding to a wind from the North-East direction.