Another issue that needs thinking is how to collect data. just one measurement of the anemometer has no meaning for itself.
We usually employ some electronic data logger that collects, averages and gives us a table as raw data. For a grass roots wind measurement system this may be more of an issue then seems, since the electronics need to be brought to location and maintained there.
I want to offer a different approach. What we eventually need from an anemometer is a histogram of wind occurrences, and we can create one without actually logging.
Let us assume the anemometer we use creates some sort of motion : it can be the balloon pooling the string or a rod in an angle, or even a tree bending in the wind. We can connect a pipette (water drops dispenser) connected to a moving rod, and put under it a line if buckets. After a long period of time the amount of water in each bucket will be proportional to the time the pipette stayed over that bucket - which should correspond to wind speed
This method still requires filling water to a tank every now and then, and the buckets may get full. For longer periods of time you can replace the buckets with a tablet of limestone - somewhat tilted perpendicular to the pipette line of movement. The drops will curve grooves into the limestone - the deeper the groove the more time spend in that wind speed.
One disadvantage: the 'log' line is not an average - the droplet falls at a certain moment, so its a histogram of momentary values -
--- so here is a challenge: devise a way to average over say 1min or 10 minutes (the standard measurement time ) using simple mechanical or fluid contraption
materials, averaging
I guess averaging happens over naturally anyway , if someone comes up with something that gives a single sample representing a 10 minute average thats great but I dont think its vital (actually we need an average of V^3...)
As for materials - glass or PET microballoons may be better than water/sand which winds up weighing a lot, e.g 0.5kg/hr (reasonable for a sand clock ) is almost a ton/month , while hollow glass microspheres are 0.2g/cc, for the same ~1/2 liter volume / hr its a more manageable 72kg/mongth (although still 360liters/mongth)
If there was a way to get the material naturally, like collecting dew or squeezing humid air that would b nice
our weather balloons -
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220615687535&ssPageNa...