sunheat

Sunheat is a colloquial term referring to thermal energy from the Sun, delivered to Earth mainly as solar radiation that heats matter. The Sun’s output spans a spectrum that includes visible light and near-infrared, with a smaller fraction of ultraviolet radiation. When this radiation reaches Earth, it may be reflected, absorbed, or transmitted by the atmosphere and surface, contributing to surface warming and to atmospheric processes. The intensity of sunheat at a location depends on solar elevation, time of day, season, latitude, weather, and the properties of surfaces exposed to the Sun. It is typically expressed as irradiance in watts per square meter (W/m^2) or as insolation over a period in kilowatt-hours per square meter per day (kWh/m^2/day).

Sunheat is a central factor in the Earth's energy balance and in climate dynamics. It also underpins a range of technologies: solar thermal systems that heat water or air for buildings, solar power plants that concentrate sunlight to produce heat for electricity generation, and, separately, solar photovoltaic devices that convert light into electrical energy, sometimes using heat management strategies. In architecture and urban design, passive solar strategies seek to maximize beneficial sunheat through orientation, glazing choices, thermal mass, shading, and insulation while reducing unwanted heat gain.

Health and safety considerations relate to ultraviolet exposure and heat stress during periods of strong sunheat. Protective measures include appropriate clothing, sunscreen, hydration, and, where necessary, shade and climate control.

Sunheat is an informal term; in scientific literature solar radiation or solar energy are the precise terms used to describe this energy.