1) Altitude angle (α ): It is defined as the angle between the central ray from the sun , and a horizontal plane containing the observer is the Solar altitude angle. At the Sunrise and Sunset the solar altitude angle(α) is zero.
2) Zenith Angle : If a vertical line is drawn to the horizontal plane at its centre the line joining sun and the centre of the plane will make an angle ɵ with this vertical . This angle is called the Zenith angle.
3) Day length (td): It is the time elapsed between sunrises to sunset. By knowing the values of sunrise and sunset hour angle, we can calculate the day length.
4) Solar Azimuth angle ( ):- It is the horizontal angle measured on plane from north to the projection of suns rays on this plane .
5) Local solar time :-This is also called as Local Apparent Time ( td) and can be calculated using various values of zenith angle . the time so calculated is called the Local Solar Time.
6) Surface azimuth angle :- ( ) : It is defined as the horizontal angle between the projection of the normal to the horizontal surface and the north south line.
7) Slope : It is also called as tilt angle ( ) . The vertical angle between one edge of a surface and its projection on the horizontal plane is called the tilt angle .
8) Declination angle (δ) : It is the angle between a line extending from the centre of the sun to the centre of the earth and the projection of this line upon the earth’s equatorial plane.