Higher Geography – Atmosphere Practice Test

When sunlight reaches Earth, how concentrated it is depends on the angle at which it hits the surface. A high Sun means rays strike more directly, concentrating energy on a smaller area and making the surface feel more intense. In polar latitudes, the Sun is low in the sky, so rays arrive at a shallow angle. That same amount of energy is spread over a larger surface area on the ground, lowering the energy per square meter. This idea is often summarized by irradiance being related to the cosine of the solar zenith angle: as the zenith angle increases (Sun lower), the irradiance decreases. So the energy effectively covers a larger area, making the insolation less intense. The other options don’t fit because the energy per unit area isn’t the same or smaller with a low Sun, and the pattern isn’t irregular—it follows the geometry of the Sun’s angle.