The earth is not a rigid solid but, is semi-molten liquid covered by a thin, solid and pliable crust. As a result, the moon-sun tidal forces produce earth tides as well as ocean tides. Twice each day the solid crust of the earth rises and falls as much as one-quarter meter. As a result, earthquakes and volcanic eruptions have a slightly higher probability of occurring when the earth is experiencing an earth spring tide, that is, near a full or new moon.

We live at the bottom of an ocean of air that also experiences tides. Being at the bottom of the atmosphere, we do not notice these tides. In the upper part of the atmosphere is the ionosphere, so named because it contains so many ions, electrically charged atoms that are the result of intense cosmic ray bombardment. Tidal effects in the ionosphere produce electric currents that alter the magnetic field that surrounds the earth. These are magnetic tides. They in turn regulate the degree to which cosmic rays penetrate into the lower atmosphere. The cosmic ray penetration affects the ionic composition of our atmosphere, which in turn is evident in subtle changes in the behaviors of living things. The highs and lows of magnetic tides are greatest when the atmosphere is having its spring tides, again, near the full and new moon.