Why is it colder in winter (January) and warmer in summer (July)?

• A. We are tilted away from the sun in January
• B. Earth is farther from the Sun in January
• C. There is more cloud cover in January
• D. Ocean currents reverse in January

Answer: (A)

Seasons are driven mainly by the tilt of Earth's axis relative to its orbit around the Sun. That 23.5-degree tilt means the Northern Hemisphere is tilted toward the Sun in summer and away from it in winter. When tilted away, sunlight hits the surface at a lower angle, spreads over a larger area, and passes through more atmosphere, so less solar energy reaches the ground. Days are shorter too, so total energy input is reduced and temperatures fall. In summer, the Sun climbs higher in the sky, light is more direct, the atmosphere path length is shorter, and days are longer, so more energy reaches the surface and temperatures rise.

Distance to the Sun changes a bit over the year, but it’s not the main driver of seasons. In fact, the Earth is closer to the Sun in January (perihelion) yet it's still winter there, which underscores that tilt—not distance—controls the seasonal pattern.