Previously, I shared a post about a conversation with my son about the rising sun viewed at different latitudes. During that conversation, we also discussed how the length of our shadow varied over the course of a year. In winter at noon in the northern hemisphere, when the sun is low in the sky, our shadows are cast long to the north. In summer, our shadows are shorter due to the higher angle of the sun in the sky.
Imagine a plane extending through the earth at the equator. Extend that equatorial plane out into space. Between late March and late September, the sun appears above that plane. It reaches its highest extent in late June at the summer solstice. The sun appears at the elevation of the plane on the equinoxes in late March and late September. It appears at its farthest extent below the equatorial plane in late December at the winter solstice. The farthest north and south of the equatorial plane reached by the sun is 23.5˚.
Normal Shadows
Melanie and I live about 42˚ north of the equator. In the summer months, the sunlight direction is above the equatorial plane several degrees. Our short shadows are cast to the north at noon. In the winter months, the sunlight direction is below the equatorial plane. Our shadows are cast longer to the north. The blue man in this figure is not to scale, but illustrates the concept of casting of shadows.
How I See It 