So, I wrote in my last post why the world urgently needed a new weather station and I set out to find a good location for the actual sensors. This process was interesting in its own right since it revealed that we have quite a few microclimates on the property.
Below is a winter photo of the house with 3 (of many more) elements that affect the microclimate:
- The star indicates a pretty dense tree cover, the majority of the house is shaded from the sun during the day by tall White Oak. Especially for wind speed and direction, this matters: Where possible measuring devices should be in a large open area away from possible interference such as building, trees etc. It is generally accepted that measurements are based on readings at 10 metres (33 feet) above ground and the distance between the anemometer and any obstruction is at least ten times the height of the obstruction! (Reference). According to this, I would go at least 10 meters higher (!) than the canopy and while that would surely be a fun project, it likely need a building permit (and look pretty ugly). More importantly, whats the point? What relevance would the windspeed 30m above the ground level have for this project?
- The arrow in the front points along a meadow toward and up to the house. Generally, the sun heats the meadow first during sunrise and a significant warm breeze comes up the little hill and hits the front of the house, channels to the left and right, even on quiet days, there is quite some wind on the deck (left) and the carport (right). By the way, in the photo, the photographer is pointing nearly exactly East.
- In the circle is the chimney which I had earmarked as permanent position for the weather station, I figured, the roof is the only place where I can guarantee that the house itself is not shading the weather station from the wind or sun. Unfortunately, the canopy shields the sensor from the full wind, at least as long as there is foliage. You can’t win, eh?
Ok, so one way or the other, readings from a single sensor hub are limited to the specific microclimate of the sensor which can be quite varied. Just exactly how varied this could be is really interesting and maybe something I explore by making a dozen or so sensors and distribute them in various places. But that is for later. For now I chose the position just over the chimney as “good enough” to be indicative of the overall climate around the house. Later I will write a little about “where on the chimney” and yes, it matters.
The process of identifying a good position was interesting since it forced me to think about the environment in context (meadow heats up -> creates higher pressure than in forest -> creates wind -> creates evaporative cooling -> …) but also made me think what I actually want out of the weather monitor. In general, I don’t really need it to understand the weather around the house. Looking out of the window is a perfectly fine method and even better is to step outside and feel it. No, the goal was to develop a system that monitors changing conditions inside a specific environment, understand the reasons behind the changes and – later interact with the environment.
The next step is to actually build the sensor and put it in place.