The MagPi - July 2018

(^74) May 2018 raspberrypi.org/magpi
Feature
(^74) July 2018 raspberrypi.org/magpi
BUILD A WEATHER STATION
YOU’VE DEALT WITH
HEAT, NOW IT’S TIME
TO TACKLE ANOTHER
ELEMENT: AIR
So far, all the sensors you’ve
used have been passive electronic
sensors that just sit there and make
measurements of their surroundings.
However, to measure things like
rainfall and wind speed/direction,
you’ll need to use active mechanical
devices that physically interact with
the environment.
The original Oracle Weather Station kit
employed popular wind and rain sensors
(magpi.cc/mkxjNE) that are used in
many consumer weather stations. These
are the recommended sensors to use, as
they are robust and reliable. Their data
sheet (magpi.cc/ibPeBX) gives more
information about the sensors’ size
and construction.
A typical anemometer
has three arms with
scoops on the end that
catch the wind, causing
the arms to spin
Above RJ11 breakout
Above The reed switch has two
metal contacts inside it that
touch each other when under
the influence of a magnet
Wind vanes show the direction the wind is coming
from, not where it’s going. This can be a little
confusing in the beginning, because the arrows on
most TV weather maps show the opposite. A wind
vane works because wind exerts force on its vertical
blade, which rotates to find the position of least wind
resistance; this position is aligned with the direction
of the oncoming wind