The autumnal equinox in the Northern Hemisphere is on September 22 or 23 and the vernal or spring equinox is on March 21 or 22. The climate for a particular location depends in large part on its energy balance. Temperature decreases from the equator to the poles. The rate of temperature change shown by the spacing of the isotherms is greater in the winter hemisphere than in the summer hemisphere. Seasonal movement of the isotherm patterns equatorward and poleward covers more latitude for land areas than for oceans.
Isotherms bend toward the equator as they cross the continents in the winter hemisphere.
Isotherms bend toward the pole as they cross the continents in the summer hemisphere.