This page describes the meteo data graphs as generated by the meteo software package. This package collects data from a Davis Instruments station into a MySQL database. The data is averaged over sampling intervals of 300, 1800, 7200 or 86400 seconds, and display in graphs spanning a day, a week, a month or a year.
The description below assumes the default colors as specified in the sample meteo.conf distributed with the package.
The red curve shows the temperature, the light red area shows the range between maximum and minimum temperature during the sampling interval. The blue curve shows the dew point, the temperature at which dew begins to form.
The blue graph shows average barometric pressure, the range between minimum and maximum pressure during the sampling interval is shown in light blue.
The lower part of the graph shows in light green the average wind speed during the sampling interval, the maximum speed is shown in dark green, scale on the left of the graph. The upper part shows the wind azimut in blue, scale on the right.
Averaging the wind is not trivial. The meteo package samples wind every few seconds and computes the displacement vector for each of this short intervals. The vectors are then all added up, the average speed is the length of the total displacement vector devided by the averaging interval (one minute).
The gold histogram shows the total solar radiation in W/m^2, scale on the left of the graph. The pink curve shows the UV index, scale on the right.
Note that after snow fall the readings of both sensors are not reliably, as the sensors are not automatically freed of the snow.
The blue histogram shows the total rain (or moisture content of snow of the precipitation) in mm during the sampling interval.
As fresh snow consists mostly of air, it isn't trivial to determine the amount of snow from the reading of the rain sensor. A factor of ten is not unusual: 7cm of fresh snow boil down to only 7mm of rain.