Diurnal changes

• Significant changes occur within a 24-hour period in the water cycle. Lower temperatures at night reduce evaporation and transpiration. Convectional precipitation, dependent on direct heating of the ground surface by the Sun, is a daytime phenomenon often falling in the afternoon when temperatures reach a maximum. This is particularly significant in climatic regions in the tropics where the bulk of precipitation is from convection storms
• Flows of carbon vary both diurnally and seasonally. During the daytime CO2 flows from the atmosphere to vegetation. At night the flux is reversed. Without sunlight, photosynthesis switches off, and vegetation loses CO2 to the atmosphere. The same diurnal pattern is observed with phytoplankton in the oceans