What is the primary cause of seasonal temperature changes in mid-latitudes?

• A. Tilt of the Earth's axis
• B. Distance to the Sun
• C. Moon phase
• D. Global wind patterns

Answer: (A)

Seasonal temperature changes in mid-latitudes happen mainly because the tilt of the Earth's axis changes how sunlight reaches the surface throughout the year. The axis is tilted about 23.5 degrees relative to its orbit around the Sun, so during different times of year the northern hemisphere is tilted toward or away from the Sun. When it’s tilted toward the Sun, the Sun climbs higher in the sky, the sunlight hits more directly, and days are longer, delivering more energy to the surface and warming temperatures. When it’s tilted away, the Sun stays lower, days are shorter, the sunlight is more oblique, and less energy reaches the ground, leading to cooler temperatures. The distance to the Sun does change a bit over the year, but that energy change is small compared to the effect of the Sun’s angle and day length. The Moon’s phase doesn’t drive seasons, and while global wind patterns shape weather, they aren’t the underlying cause of the regular hemispheric temperature cycle.