I have built several weather stations over the years, the latest incarnation is based on a Raspberry Pi mini computer as opposed to the previous Arduino micro controller. This gives me more flexibility and increased processing power while still having the ability to interface with most weather sensors, except it does not support analog inputs.
The whole system is split into two main parts, the outstation including sensors and the indoor system running on a desktop PC.
The heart of the outstation is a Raspberry Pi computer running a version of GNU/Linux known as Raspian a derivative of Debian Linux.
The sensors are connected to the on-board GPIO (General Purpose Input Output) pins via a ribbon cable to a home made interface PCB, which has physical connectors to plug in the sensors and a A/D converter so the Pi can read analog inputs.
The sensors include:
- BME280 Temperature / Pressure / Humidity
- 2x DS18B20 Temperature sensors for Grass and Soil
- BPW34 Photo-diode for Light intensity
- Rain Gauge, Anemometer and Wind Vane from Argent Data system (as sold as replacement parts by Maplin's)
The analog inputs are converted to digital signals by a MCP3008 A/D converter chip, this is for the Light levels and wind direction.
The software on the outstation to read all of the sensors, written in Python loops around all of the sensors every 60 Seconds and records the raw data in a database
The computer and interface board is in a waterproof housing and mounted 1.5m above ground on a 6m pole, with the wind and light instruments at the top and temperature/pressure sensors in a home made radiation screen below the main housing. Sensors for soil and grass temperature are on and under the lawn at a distance of 5m, the rain gauge is mounted with a web camera at a hight of 2.5m.
Every 15 minutes a script on the pc is run which synchronizes the weather directory on the outstation with the weather directory on the pc. This includes the database and images from USB camera's, a python script loads data from the outstation database and performs some calculations to generate additional parameters then saves the data to the master database. Then the instrument graphic is constructed and a web page is built before updating the web server
Xtide is used for tidal data and a python script based on Zambretti Forecaster with modified equations for the simple weather forecast.
This is the weather headline and is produced up to 9am then fixed at 9am for the rest of the day.
I have also included a Sager Weathercast algorithm for producing another simple forecast also implemented in python.
This is updated continuously throughout the day.
Each night a python script to generate daily and monthly totals is run and the master database is updated.
To display weather data on the PC, i have again used python/tk GUI to display data and enter manual weather observations.
Nagretti and Zambra were scientific instrument makers in London around 1900, They produced a circular weather 'slide rule'
using the wind direction, pressure, pressure trend and season to predict the general weather.
The reverse of the instrument had a list of the predictions according to the letter produced by the rotating disks.
This only produces 26 separate indications, this is supposed to be up to 95% accurate, but is very general.
The Sager Weathercaster is a book by Raymond M. Sager (Meteorologist) published 1969 by October House, New York
It contains a revolving dial of 4 disks similar to the Zambretti forecaster and a set of tables to decode the numbers produced by the dial.
This produces over 1500 distinct forecasts, and gives a general forecast and an indication of future wind and temperature.
The python code is derived from a java-script by Naish666, This is basically a lookup table of all the input data (Wind direction and change, Pressure and trend, Clouds/Rain)
In the future i want to develop a simple weather model for predicting local short range forecasts with data from airport METAR reports.
I am also working on building an antenna to enable me to receive images from NOAA polar orbiting weather satellites. More..
Please note: All of the information on this web site is generated by software i have developed and is for personal interest only.
It is not intended as an official representation of the state of the weather in or around County Durham.
While i try to make all information as accurate as possible it may contain errors or omissions.
Official UK weather provider: Met Office