Earth's 23.5 Degree Tilt: The Reason for Seasons 

You may have already known that the timing and intensity of seasonal change is different in many parts of the globe. Here in the Northern Hemisphere, we would expect winter conditions in the months of December, January, and February, whereas a location below the equator - like Australia - the opposite would occur.
In this animated short, Adelynn Puett explains how the Earth's slight tilt influences seasonal patterns at different proximities to the equator.