These graphs are created using a software package called RRDTool running on a Linux PC in my house.
The temperature is being detected by a thermistor outside the window connected to the joystick port.
The whole thing was calibrated against an Oregon Scientific Indoor/Outdoor thermometer.
Though the thermistor is in the shade, the wall below tends to be heated by direct sunlight during the afternoon.
This heating gives a jagged line on partially cloudy afternoons.
It also tends to make Nottingham look tropical on sunny days - which is completely wrong.
On the graph below the difference between the daytime high and the nighttime low gives an idea of how clear the sky was.
Clearer weather means warmer days and colder nights.
Other Stuff
The Infrared Webcam Page
My Chess Race animation on YouTube (Opens in a new window)
Macro (Close Up) Photography with a hacked digital camera
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