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 book The Weather Observer’s Handbook (published by Cambridge University Press), 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
The traditional method of measuring humidity is by using a pair of matched mercury-in-glass thermometers, known individually as dry-bulb and wet-bulb thermometers and in combination as a dry- and wet-bulb psychrometer. The wet-bulb is a thermometer whose bulb is kept permanently wet using a thin close-fitting cotton cap or sleeve. The wet-bulb is cooled by evaporation, and the difference in temperature between dry-bulb and wet-bulb thermometers is a measure of the humidity of the air. Using tables, an online calculator or formulae, the relative humidity (or any of the other humidity measures) can be quickly and easily determined from simultaneous readings of the two thermometers.
Radiation from the Sun consists of a wide range of wavelengths, from extreme ultraviolet to the far infrared, peaking in the visible region. Solar radiation is amongst the most variable of all weather elements, and consists of two main components – direct solar radiation from the solar disk, and diffuse solar radiation from the rest of the sky, the latter as a result of the scattering and reflection of the direct beam in its passage through the atmosphere.
‘Precipitation’ measurements include rain, drizzle, snow, sleet, hail and the like as well as the occasional minor contribution from dew, frost or fog. Precipitation is highly variable in both space and time, and precipitation measurement networks are usually denser than for other elements to improve spatial coverage. There may be as many as 1 million raingauges operating globally, although standards vary from country to country.
Precipitation measurements are very sensitive to exposure – particularly to the wind – and the choice of site is very important to ensure comparable and consistent records are obtained. Choose an unsheltered (but not too exposed) spot for the raingauge/s – loss of catch through wind effects is the greatest single error in precipitation measurements, particularly in snow. A site on short grass or gravel is preferable. Wherever possible, obstructions (particularly upwind obstructions in the direction of the prevailing rain-bearing winds) should be at least twice their height away from the raingauge. Rooftop sites are particularly vulnerable to wind effects and should be avoided. The site should also be secure, but accessible for maintenance (grass cutting, etc.) as required.
There are enormous differences in functionality and capability between basic and advanced models of automatic weather station (AWS). The general rule that ‘you get what you pay for’ holds true for AWSs as well as most other products, but some systems are better than others and it pays to check available products carefully against your requirements to ensure the best fit.