Rock with an Attitude, Grand Gulch, Utah
The Tropic of Cancer is the most northerly latitude where the sun can appear directly overhead at noon. If a mountain is located north of the Tropic of Cancer (or south of the Tropic of Capricorn in the Southern Hemisphere), the sun does not shine directly on the north side at noon, even during the summer solstice.
But this is only true at noon. During the morning and evening the situation changes. Figure 1 shows the zenith and azimuth angles of the sun during winter solstice, spring/fall (equinox), and the summer solstice for a mid latitude location. The zenith angle is the angle between the sun and the spot directly overhead. Zero zenith angle means the sun is directly overhead and 90 degrees means the sun is rising or setting. The azimuth angle is the compass direction to the sun. In the winter the sun rises in the southeast and sets in the southwest. During the summer the sun rises in the northeast and sets in the southwest. At the equinox the sun rises in the east and sets in the west.
Figure 1. Azimuth and zenith angles in degrees for a mid latitude location.
The net result is that, if other mountains or ridges are not blocking the view, the sun does reach a north wall during the summer in the morning and evening, but not at noon.
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Copyright 2014 John Walton