There are sensors sensitive enough to pick up minute changes in ... It takes some work, but it's still more than doable with a bit of time and patience. There are hundreds of different Arduino builds ...

The sensor shown here is essentially two plates mounted side-by-side, attached to an Arduino Nano using the ... with a dielectric constant that is different enough from the air surrounding the ...

The easy way is to use the Arduino-powered Norman climate simulator from [934Virginia] which leverages data from different locations ... target climate and actual sensor readings in your greenhouse.