In June the northern hemisphere is tiled towards the sun and in December the Southern Hemisphere is most tilted towards the sun so in spring/autumn wouldn’t the equator be most towards the sun so it would be hotter?
In: Physics
The change is small. The intensity of the suns rays on the equator at the solstices relative to the equinox is cos(23.43 degrees) or 91.7%.
By contrast the swing is Minneapolis goes from cos(45-23.43) to cos(45+23.43) which calculates to a swing from 36.8% to 93.0% which is very large… a factor of over two and half.
Meteorologists will point out that the 8.3% swing at the equator can probably be seen in the weather patterns somehow… when the rains come, etc, but it’s pretty small compared to more temperature areas.
The tilt towards the sun does affect the amount of energy you get from the sun per unit area but that is only part of the story in terms of seasonal temperatures.
Altitude, air currents, ocean currents, distance to the sea etc all play a huge role in determining the ground and more importantly air temperature of your area.
Since land heats up faster than water, if the air currents push the hot air away and bring cooler air from the sea, you’re going to feel cooler.
Oh my gosh I spent so long trying to explain this to my coworkers just the other day – the northern and southern climes have one maximum and one minimum of solar intensity per year, but the equator has two maxes and two minima. They just would not buy it, pointing out that of course the equator is hotter, as it was tropical. Drove me crazy.
Edit: great answers here. Thanks everyone!
The effect of the sun being closest in January (7%) is almost as great as the angle being more favourable in March and September (8%). That leaves just July as the coldest month. As noted by other commenters, these effects are all tiny compared to the big seasonal changes outside the tropics.
The equator experiences relatively consistent temperatures throughout the year due to its proximity to the sun. During the spring and autumn equinoxes, the sun is directly overhead at the equator, resulting in roughly equal day and night lengths. This can contribute to more consistent temperatures, but the equator generally experiences warm temperatures year-round due to its position relative to the sun.
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