Will wind driven rain throw off accuracy of total rainfall?


#1

Wondering if there was any thought to the potential for higher than normal rain rate AND rainfall rates resulting in a wind driven rain with Sky over a traditional plastic cylinder.

At the beach - we get strong winds that accelerate the speed at which rain drops hit structures. While I don’t have a WF system to test against a traditional cylinder gauge - the rain total with a cylinder will never over-state total rainfall because of wind accelerating falling rain drops. Wondering if the impact of wind driven drops artificially inflate rain rates & totals given the technology used in Sky.

Interested in field tester’s thoughts?

Gary L.


#2

Yes, there are previous topics on this matter.


#3

Hi Gary,

In the topic ‘rain sensor and vibrations’ there is some discussion about this. In my case I am comparing a Sky 12m above ground level with 2 plastic funnel style of rain gauges. The conventional funnel gauges are on the fence several meters from buildings. But during heavy storms the rain bounces off the roof and increases the amount in either of the gauges. So I then average the 2 plastic gauges to compare with the Sky. Currently the readings from the Sky can be very close and other times way off so I would not use my Sky at this stage to monitor my rainfall. But the future is exciting and unknown?
cheers Ian :slight_smile:


#4

A couple of weeks ago, I had a massive but short storm here and loads of water were blown into the slot where the wind is measured. After the storm, the relative humidity was in the upper 90s and there was little wind to create evaporation from the slot. It showed considerable wind (about 2 m/s) for several hours after the storm had finished, even though there was no wind. I ascribe this to water drops adhering to the upper surface of the slot. I haven’t seen the same phenomenon since, despite a few storms but the latter were not so violent as the one I describe. I’m not able to say whether the adherent water was on the four electrodes or on the insulation between them.

Incidentally, the amount of precipitation measured on my two “conventional” weather systems after the storm was respectively 28.5 and 30.6 mm, but SKY registered only about 14 mm. This did not surprise me as those 30 mm of rain fell in a matter of a few minutes with wind speeds over 10 m/s. I wonder how many droplets of rain were blown over the top of the unit?


#5

thank you for reporting this. I live on the beach and we regularly have wind drive rain out of the east with 30-50mph winds. While I don’t have Sky yet, I’ll be studying the impact of high winds and rainfall rate and totals against more traditional means of measurement (tipping bucket, cylinder for rain and anemometer cups for rain). I’ll be sure to you, other field folks and developers know my findings. Again glad you shared this important information as the most challenging aspect of developing the new standard of care for affordable home weather stations will be the extreme weather events.