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
Instrument calibrations are one of the most important, yet also one of the most neglected, areas of weather measurement. Making accurate weather measurements requires accurately calibrated instruments.
Most air temperature measurements are now made using resistance temperature devices (RTDs), which are steadily replacing liquid-in-glass thermometers. The main types of sensor in use today are the platinum resistance thermometer and the thermistor. The former is more accurate and more repeatable, but more expensive. Both can be made very small and thus highly responsive.
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.
Voluntary observers provide the backbone of most countries observing networks, and tend to do so for many years. There are examples within the UK and the United States of a few individuals completing 70 years or more of high-quality weather records. Without doubt, the longer the record, the more interesting it becomes to look back upon notable events.
Spreadsheets are ideal for archiving weather records, and provide more comprehensive analysis and presentation tools than the AWS software used to store sensor output. Holding and archiving data in hourly, daily and monthly spreadsheets is easy to do, simplifies record-keeping and makes subsequent analysis much more straightforward.