Hi,
IIRC the collection area is between 60 and 65 square cms, but it's not of much significance unless you know the volume of the "buckets". Also, the main "complaint" about the FO rain gauge is the very low gradient of the "funnel" and the low height of the side walls. So the recorded value can be low due to "splash out".
Personally, I have added a 14 cm diameter funnel, which increases the sensitivity by a factor of about 2.5. But unfortunately it doesn't actually give any earlier indication of "first rain" unless using a treatment such as "Rain X" to prevent surface tension holding drops in the funnel.
Cheers, Alan.
IIRC the collection area is between 60 and 65 square cms, but it's not of much significance unless you know the volume of the "buckets". Also, the main "complaint" about the FO rain gauge is the very low gradient of the "funnel" and the low height of the side walls. So the recorded value can be low due to "splash out".
Personally, I have added a 14 cm diameter funnel, which increases the sensitivity by a factor of about 2.5. But unfortunately it doesn't actually give any earlier indication of "first rain" unless using a treatment such as "Rain X" to prevent surface tension holding drops in the funnel.
Cheers, Alan.