This site provides useful practical information related to global and national weather observing practices and instruments, including independent equipment reviews.
You will find much of the background in my new book The Weather Observer’s Handbook (Cambridge University Press, 2012), details of which can also be found on this site, together with useful links and downloads.
Author, The Weather Observer’s Handbook
A nation obsessed with the weather? Yes, certainly, but which nation?
Tip of The Day
It is advisable to check and test all sensor / datalogger / software and communications thoroughly, over a period of at least a few days, before permanent hardware installation or embarking on any long-term data collection.
‘Humidity’ refers to the amount of water vapour in the air, a vital component of the weather machine. Various measures are used to quantify the amount of atmospheric water vapour – relative humidity and dew point being the two most commonly used. Knowledge of any two values can derive other humidity parameters. The amount of water vapour that the air can hold varies significantly with temperature – saturated air at 0 °C holds only a quarter of the amount that saturated air at 20 °C can hold.
When choosing a weather station, or components of a weather station, decide firstly what the equipment will mainly be used for: some potential uses may not be immediately obvious. Once that is clear, review the relevant decision-making factors as outlined in The Weather Observer's Handbook, Chapter 2, then prioritize them against your requirements.
The most common measurements made are of sunshine duration, using a sunshine recorder, and global solar radiation on a horizontal surface, using a pyranometer. ‘Sunshine’ is defined in terms of the intensity of a perpendicular beam of solar radiation from the solar disk. The intensity of solar radiation is measured in Watts per square metre (W/m2), and daily totals in Megajoules per square metre (MJ/m2). Sunshine durations are measured in hours, or quoted as a percentage of the maximum possible duration.
Grass and earth temperatures are the most commonly observed temperature measurements, after air temperature. The lowest temperatures on a clear night will be recorded at or close to ground level. Where the surface is covered by short grass, the lowest temperatures are attained just above the tips of the grass blades. The so-called ‘grass minimum temperature’ (or ‘grass min’) is measured using a thermometer or electrical sensor freely exposed in this position. A ‘ground frost’ occurs when the grass minimum falls below 0°C.