Short term changes to the cycles and the significance of these changes, including diurnal and seasonal changes of climate, temperature, sunlight and foliage

  • Created by: EmilyM17
  • Created on: 22-05-19 09:58
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  • Short term changes to the cycles and the significance of these changes, including diurnal and seasonal changes of climate, temperature, sunlight and foliage
    • Diurnal changes
      • Occur within a 24 hour period
      • Water
        • Lower temperatures at night reduce evaporation and transpiration
        • Convectional precipitation, dependant on heating of the ground surface, often falls during the afternoon when temperatures reach a maximum
          • Particularly significant in climatic regions in the tropics where the bulk of precipitation is from convectional storms
      • Carbon
        • During 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
    • Seasonal changes
      • Controlled by variations in the intensity of solar radiation
      • WATER-EXAMPLE
        • UK
          • Solar intensity peaks in mid-June and falls in December
            • As a result evaporation is highest in the summer months and lowers in the winter
      • CARBON
        • Seasonal variations shown by month-to-month changes in net primary productivity (NPP)
          • In middle to high latitudes, day length (photoperiod), and temperature drive seasonal changes in NPP
          • During the northern hemisphere summer, when trees are in full foliage, there is a net global flow of CO2 from the atmosphere to the biosphere. This causes atmospheric CO2 levels to fall by 2 ppm.
            • At the end of the summer, as photosynthesis ends the flow is reversed with natural decomposition releasing the CO2 back to the atmosphere
          • Seasonal fluctuations in the global CO2 flux are explained by the concentration of continental land masses in the northern hemisphere. During the growing season ecosystems such as the boreal and temperate forests extract huge amounts of CO2 from the atmosphere which has a global impact.
          • In oceans, phytoplankton are stimulated into photosynthetic activity by rising water temperatures, more intense sunlight and the lengthening photoperiod.

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