axial parallelism
... that the axial parallelism of the Earth's tilted axis is the reason we have winter, spring, summer and fall?
... that the <b id="mwAaA"><a href="./Axial_parallelism" id="mwAaE" rel="mw:WikiLink" title="Axial parallelism">axial parallelism</a></b> <i id="mwAaI">(diagram pictured)</i> of the Earth's <a href="./Axial_tilt" id="mwAaM" rel="mw:WikiLink" title="Axial tilt">tilted axis</a> is the reason we have winter, spring, summer and fall?<!-- special occasion, 12/21 -->