The Hum level is observed to make considerable variations that can be traced to three main causes.
First is the daily cycle caused by the changing voltage on the power grid, this reaches a maximum at about 1 to 2 am each day. Second is the daily cycle of the ionosphere that takes place between sunset and sunrise. These two cycles are fairly constant and predicable, however, the ionosphere is dependant upon solar activity such as sunspots that can be very erratic. The third variation is caused by the weather, in particular the boundary between high and low pressure systems. It is possible to predict changes ijn Hum level using weather forecast charts. -- 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.
