This page is page is intended for getting started with 1D simulations.

Horizon files

There are two types of horizon files:

  1. for METEO stations;
  2. for points, in point-simulations only.

The general idea is that every point P (x,y,z) on the landscape, unless in the middle of a flat terrain, is shaded by the surrounding objects (mountains, buildings, trees, etc..). These objects produce a cast shadow on P. This prevents the point from getting the radiation as a function of its position (lat, long) and the day time.

  • Distributed simulations: the calculation of the cast

shadow effect is carried out for every pixel (by the routine shadow_n);

  • Point-simulations: since the topography is not provided,

the user must specify this information in the horizon file. Hence, an horizon file is required for every simulated point. Unless given, the model creates one assuming an overall flat terrain.

The horizon file can be given in input also for the METEO station. In this case it is needed to set the time when the sun is obscured by the obstacle; from that time onward the cloudiness calculation is carried accounting for the shade generated on the station since the ratio between actual and potential radiation would no longer provide a reliable value.

How to build this file The idea is to discretize the 2D horizontal space (x,y) around a point, P, using an azimuth pace user-defined and, for each pace and for a given distance (the planar distance,r, between the point and the obstacle), a vertical angle (in the plane (z ,r), where r is the radius connecting the point and the object) is provided to describe the height of the object. The file structure is a (Nx2)matrix whose first column represents the azimuth angle and the second column the elevation angle of the object height. N is the number of azimuth discretization pace defined by the user.