Why is the Northern Hemisphere colder in January than in July?

The Northern Hemisphere experiences colder temperatures in January primarily because of the tilt of the Earth's axis. During this time, the axis is tilted away from the sun, causing solar rays to strike the surface at a more oblique angle. This results in less direct sunlight and consequently cooler temperatures.

In contrast, during July, the Northern Hemisphere is tilted toward the sun, allowing for direct sunlight to hit the surface more intensely, which contributes to warmer temperatures.

This concept explains the seasonal temperature variations experienced across the planet. Other factors, such as the distance from the sun as well as variations in daylight hours and the intensity of solar radiation, also play a role, but the axial tilt is the primary reason for the significant temperature differences between these two months.