Although the Hum level may vary at various times there is a constant underling daily pattern that can easily be recognised. The Hum level begins to increase at about sunset reaching a maximum between 2 and 3 am . This is followed by a steady decrease reaching a minimum about one hour after sunrise.
There are two daily cycles related to this. First is the voltage on the power grid. This also goes through a daily cycle , increasing during the evening and reaching a maximum at about 2 am then falls to a minimum at about 11 am. This approximately follows the same sequence as the Hum level. Second is the daily cycle of the F layer in the ionosphere. The F layer exists as 2 layers during the day and merges to a single layer after sunset. The F layer is also greatly influences by sunspot activity The Hum level is also affected by the weather, in particular the pressure gradient that exists between high and low pressure weather systems, however, these changes are erratic and easily distinguished from a regular daily cycle. -- You received this message because you are subscribed to the Google Groups "Hum Sufferers" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/hum-sufferers. For more options, visit https://groups.google.com/d/optout.
