Rain Totals

The majority of automatic weather stations record rainfall by way a pair of small tipping buckets fed via a funnel of a defined size. The idea of the tipping buckets is that rain is fed via the funnel into each bucket in turn until a balance tipping point is passed, when this point is reached the bucket collecting the rain tips, empting its rain and moving the second bucket into position to collect more rain. Each tip of a bucket operates a reed relay switch registering a set quantity of rain, usually about 0.2mm which is added to the total rain for the day. The advantage of using a switch to register rain is that you can count operations over time to give an idea of rain rate per hour.

                   

This first set of graphs of rainfall show single current quantities for “yesterday”, “today”, “the last 7 days”, “this month”, and so far “this year”.

    

The Rain “whole hour” and rain “last 60 minutes” show graphs of rain as they increase over time. The first graph is for the last whole hour, so if the time is now 10:30 then the graph will be from 9:00 to 10:00, and over this period if it rains you should be able to see when rain fell and from the slope whether it was heavy or light. The “last 60 minutes” graph will show similar rain data but the period will be from now to one hour ago.

    

The “24 Hour” graph is very similar to the hour graphs in that you get an up sloping graph reading from left to right over time, giving some ideal of the rain and the rain rate. The “7 Day” graph is a bar chart graph again reading from left to right which means that today is not on the graph and should not be confused with the day on the far left.

    

Finally we have the “31 day” and “full year” graphs giving the last 31 days and the last 12 months from today. Please note that all these graphs do not update automatically, you will need to refresh the screen for that.