I started measuring meteorological data on my balcony out of curiosity and comparing it to professionally gathered data from a nearby weather station.
What do I want to answer?
How different are the temperature and humidity between my balcony and a nearby (~ 2 km distance as the crow flies) meteorological weather station.
- How large are the temperature differences?
- are these differences more pronounced in the morning (direct sunlight), afternoon or night?
- how do they vary from month to month?
- what do the temperature curves, for lack of a better description, look like qualitatively? Are the peaks sharper or less sharp for the balcony?
- How large is the difference in relative humidity?
What is the motivation behind the project?
I noticed my balcony quickly gets dry and is fairly warm.
I read about fruit walls (https://www.lowtechmagazine.com/2015/12/fruit-walls-urban-farming.html) that were used to create favorable micro climates by storing heat from the sun and sheltering the crops from wind.
Supposedly, the temperature differences could be up to 10 °C compared to their surroundings. This allowed the growing of fruit, e.g. peaches in more northern latitudes than before. Some fruit walls were even heated.
I figured my apartment block might create similar conditions. There is a large thermal mass because it’s a giant block of concrete. Circulation of air is going to be less because it has a solid guardrail, there are boundary layers and stuff I can’t even fathom.
The apartments are heated . They legally have to be from the start of October to the end of April but I suspect they are heated longer.
I know other cultures exploited micro climates for their agriculture (e.g. in the Andes, https://en.wikipedia.org/wiki/And%C3%A9n). I doubt this project is going to influence what I plant on my balcony, this is purely out of curiosity and to use the sensors that are lying around.
How is the balcony situated?
The balcony I measure is oriented roughly towards the East.
Direct insolation occurs from a bit after sunrise (15 to 30 minutes) until about noon.
Where do I get external data from?
Meteorological data from MeteoSwiss is openly available
- https://opendata.swiss/de/dataset/messwerte-lufttemperatur-2-m-10-min-mittel/resource/09066670-000d-4de5-aafc-99d040b25089
- https://opendata.swiss/de/dataset/messwerte-relative-luftfeuchtigkeit-10-min-mittel/
I also get wind speed and precipitation data even if they’re not used in this project.
More on how I query the data later.
For my own balcony, I assembled a micro controller with a real-time clock, a temperature and humidity sensor and an SD module for reading/writing. The exact setup follows in a later post.
Any preliminary result?
Yes. After about 5 months, the differences are not as large as I thought they would be.
Temperature differences skew around 2 °C warmer on the balcony.
Why this format?
I’d like to exercise learning in public, hence using a blog.
Part of it is technical but I think it’s always advisable to practice writing.
I chose the headings to be explicit questions because I think it is clearer and lessens cognitive load for the reader in a number of ways:
- It also focuses me on writing more to the point.
- It shows more of the cognitive process of this project.
- An easy question for the reader is “Is this question answered by the following section?”
The inspiration is from this excellent article: https://andymatuschak.org/books/. I have no didactic training, this is a small experiment in a different format.