text: Outdoors, DLI values vary depending on latitude, time of year, and cloud cover. Occasionally, values over 70 mol·m·d can be reached at bright summer days at some locations. Monthly-averaged DLI values range between 20-40 in the tropics, 15-60 at 30° latitude and 1-40 at 60° latitude. For plants growing in the shade of taller plants, such as on the forest floor, DLI may be less than 1 mol·m·d, even in summer. 
  In greenhouses, 30-70% of the outside light will be absorbed or reflected by the glass and other greenhouse structures.  DLI levels in greenhouses therefore rarely exceed 30 mol·m·d. In growth chambers, values between 10 and 30 mol·m·d are most common. New light modules are now available for the horticultural industry, where light intensity of the lamps used in glasshouses is regulated such that plants receive a set value of DLI, independent of outside weather conditions.