I have read in many places how a drop in temperature overnight is advantageous and is often required to trigger flowering in many species. So with a view to better understanding whats going on in my growing areas I have been keeping track of day and night time minimum and maximum temperatures and light levels at noon. My first question is, should I be looking at the maximum day time temperatures against the minimum night time temperatures? If this is correct then all is well as I am getting the desired drop in temperature overnight. However, if I look at average night time temperatures against average daytime temperatures then there is little difference. My second question relates to light. For those of you who like to quantify this, how do you actually go about measuring it? I can see that indoors under artificial light this is going to be relatively easy as the light source will have a relatively constant output. With natural light what is the appropriate way of measuring it?