This integrated solar irradiance is called solar irradiation, solar exposure, solar insolation, or insolation. The African humid period has been explained by increased insolation during Northern Hemisphere summer. They are then differentiated according to the insolation, temperature, and precipitation of snow and rain. Surface and air temperatures, insolation, and wind all affect this. In addition to lower insolation in winter, the Northeast Monsoon contributes to colder conditions. One Sun is a unit of power flux, not a standard value for actual insolation. The hornet's digging is correlated with insolation (solar energy). Day length and insolation intensity also controls the extent of the photic zone. El Tatio further features high ultraviolet (UV) insolation. This topographic asymmetry is probably due to differences in insolation. The local topography, however, also contributes significantly to the low insolation. The payback period is shorter given greater insolation. The two effects work in opposite directions, resulting in less extreme variations in insolation. During winter, the Chaco Low weakens as a result of lower insolation. Calculators are available for estimating insolation at a site.