Saturday, November 28, 2015

Rainfall Records & Rain Gauges

When I first came to Hawaii, I knew very little about the weather here and sunlight cycles. Hawaii is always paradise, no? So why worry about it, right? I was aware enough to know that this wasn't a good approach. So what was paradise really like? 

Among the first things I purchased when we arrived were an outdoor thermometer and a rain gauge. Every day at 5 a.m. and again at 2 p.m. I recorded the temperature. Every morning at 7 a.m. I recorded the rain amount. I also kept daily records about sunshine. When did the sun first hit the roof, at what angle, how many hours a day did we get full sun, and what were those hours. This sun data became valuable with our future solar electric project. 

Getting an idea about the rain patterns I knew would be important., too Afterall, I wanted to grow gardens of food and flowers. So I became diligent about keeping records. Over the years I used the exact same rain gauge (the orange one pictured below) so that my measurements would have consistent meaning. Well it isn't exactly the same one because along the way some of the gauges wore out from the tropical sunlight, one got stolen by one of the dogs and chewed up into tiny pieces, another I accidently broke. But they were all the same type. 

Just recently I started posting my rain data to COCORAHS website. So I needed a better rain gauge, one that everybody else in COCORAHS was using. So I bought the one pictured below.

It's one very nice gauge. Easy to set up. Easy to use. Easy to clean. Easy to read. The gauge has a central cylinder that lifts out for reading and an outer larger cyclinder to collect rains over one inch. Picture below is the inner core that I've removed so that I can read the rain amount.

I got mine on course. If one lives in Hawaii, one often becomes a regular customer on Amazon Prime. 

Anyway, back to rain. 

It was interesting to learn that most of my rain occurs at night. And most comes in small increments. Occasional rains bring 3"-5". Really heavy rains don't happen too frequently. Some years I get 60 to 80 inches of rain. Other times it's only 15 to 30 inches. Drought seems to be cyclic. 

Since I get almost all my water via the rain, I'm very conscious of rainfall amounts. It took a few years to get a good sense about the rain, to discover which seasons and months tend to bring the most rain. And that's quite important when it comes to figuring out when to plant various crops. 

Oh one other thing I learned while keeping rain records, the amount of rain one gets here varies considerably from place to place. Elevation has a big bearing on the amount of rain, but also location relative to the tradewinds and the volcano. Surprisingly, even one mile can make a significant difference. 

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