Solar azimuth angle be interpreted as the angle between zero and 180 degrees when the hour angle, "h", is negative (morning) and the angle between 180 and 360 degrees when the hour angle, "h", is positive (afternoon). (These two formulas are equivalent if you assume the "solar elevation angle" approximation formula). The formulas use the following terminology: Solar azimuth angle The solar azimuth angle is the azimuth angle of the Sun's position. This horizontal coordinate defines the Sun's relative direction along the local horizon, whereas the solar zenith angle (or its complementary angle solar elevation) defines the Sun's apparent altitude. There are several
Perceived visual angle Ono & Mapp (2006) noted, it unfortunately has been ignored in many current theories of size perception, and size illusions. The object's other perceived endpoint, A′, has a perceived direction "d′";, about which the observer might say "it appears toward a higher elevation than point B′." The difference between the two perceived directions () is the perceived visual angle "θ′", also called the perceived angular size or apparent angular size. It is not easy to quantify "θ′". For instance, a well-trained observer might say that point A′ "looks about 25 degrees higher" than B′, but most cannot reliably say how