next up previous
Next: Ecliptic Ascensions Up: Spherical Astronomy Previous: Equinoxes and Solstices

Terrestrial Climes

Table 4 specifies the length of the longest day, as well as the altitude of the sun when it culminates at the meridian on the days of the equinoxes and solstices, calculated for a set of observation sites in the northern hemisphere with equally spaced terrestrial latitudes. This table was constructed using the formulae in the previous section. The table can be adapted to observation sites in the earth's southern hemisphere via the following simple transformation: $L\rightarrow -L$, Summer $\leftrightarrow$ Winter, N $\leftrightarrow$ S. For instance, at a latitude of $-10^\circ$, the longest day, which corresponds to the winter solstice, is of length $12^h35^m$. Moreover, on this day, the sun's upper transit is south of the zenith, at an altitude of $+76^\circ 34'$.

Richard Fitzpatrick 2010-07-21