irradiance

Irradiance is the density of radiation that falls on a surface, typically measured in watts per square centimeter or square meter. This radiant energy originates from sources like the Sun, where nuclear fusion releases immense energy that travels through space. A square meter of Earth's atmosphere, perpendicular to the Sun's rays, receives about 1,365 watts of solar power.12

This solar energy is crucial for Earth's climate, driving atmospheric and oceanic currents and sustaining life through processes like photosynthesis. While about 31% of incoming solar radiation is reflected back into space, the remainder powers global weather patterns and determines Earth's average temperature. The intensity of this solar energy varies based on factors like latitude, time of year, and time of day.23