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Fact sheets

The Library has produced a number of fact sheets to give an introduction to various aspects of meteorology.

	1. Clouds The classification of clouds is based upon that originated by Luke Howard (1772-1864), a London pharmacist and amateur meteorologist. In 1803 Howard, wrote a book entitled 'The Modifications of Clouds' and named the various cloud structures he had studied... Download Fact Sheet 1 (PDF, 1.3 Mb)		2. Thunderstorms Most thunderstorms are associated with towering clouds known as cumulonimbus. These clouds usually form on warm sunny days or on a cold front if conditions are right for their formation. Moist air near the ground rises as it warms and if cooled sufficiently cumulus clouds form at the condensation level... Download Fact Sheet 2 (PDF, 1.2 Mb)

	3. Water in the atmosphere When a jug full of iced drink is taken out of the refrigerator, water droplets condense on the outside of the container. This happens because the jug is at a lower temperature than the dew point of the air. 'Dew point' is defined as the temperature at which the air, when cooled, will just become saturated... Download Fact Sheet 3 (PDF, 1.1 Mb)		4. Climate of the British Isles The British Isles lie in the latitude of predominantly westerly winds where depressions and fronts move bands of cloud and rain eastwards or north-eastwards across the North Atlantic. Between the depressions there are often small mobile anticyclones bringing welcome fair weather... Download Fact Sheet 4 (PDF, 1.5 Mb)

	5. White Christmases Snow at Christmas is deep-seated in British culture, and many of us long for the likes of the scenes depicted on traditional Christmas cards. The interest in snowy Christmases has its origins in the colder climate of 1550-1850 when Britain was in the grip of the 'Little Ice Age'... Download Fact Sheet 5 (PDF, 146 kb)		6. The Beaufort Scale It is often said that Francis Beaufort, of the British Royal Navy, was the first to devise a scale of wind force — towards the start of the 19th century. However, in reality he was not, in fact, the originator of such a scale. A similar one was actually in use at least a century earlier — and probably long before that... Download Fact Sheet 6 (PDF, 1.0 Mb)

	7. Climate of southwest England The counties included in this area are Cornwall, Devon, Somerset together with the Isles of Scilly. A brief description of the landscape and topography is included here, followed by statistics on temperature, sunshine, rainfall, snowfall and wind... Download Fact Sheet 7 (PDF, 1.0 Mb)		8. The shipping forecast The Met Office was established as the Meteorological Department of the Board of Trade in 1854 when Captain, later Vice Admiral, Robert FitzRoy became its first head. FitzRoy introduced the first storm warning service for shipping in 1861... Download Fact Sheet 8 (PDF, 867 Kb)

	9. Weather extremes We can all recall weather we have experienced which seemed 'extreme' or remarkable. In fact the Met Office and others in the UK and elsewhere have been recording extremes of temperature, sunshine, rainfall, snow, wind and atmospheric pressure; a number of these are summarised here... Download Fact Sheet 9 (PDF, 347 kb)		10. Air masses and weather fronts Air masses are parcels of air that bring distinctive weather features, the air making up an air mass is very uniform in temperature and humidity. Air masses are separated by transition zones or boundaries that may be more sharply defined; these are called fronts... Download Fact Sheet 10 (PDF, 853 kb)

	11. Interpreting weather charts On a weather chart, lines joining places with equal sea-level pressures are called isobars. Charts showing isobars are useful because they identify features such as anticyclones (areas of high pressure), depressions (areas of low pressure), troughs and ridges which are associated with particular kinds of weather... Download Fact Sheet 11 (PDF, 1.1 Mb)		12. National Meteorological Archive material The Meteorological Office, then located at its Headquarters at South Kensington, London, at a meeting of the Meteorological Committee on 29 April 1914, accepted the responsibility of custodian of appropriate Public Records... Download Fact Sheet 12 (PDF, 1.2 Mb)

	13. Upper-air observations and the tephigram Knowledge of temperature, humidity and wind at levels well above the ground form an essential part of the meteorologist's basic data. The state of the upper air can be obtained in many ways, but the main one is by observations from balloon-borne equipment... Download Fact Sheet 13 (PDF, 700 kb)		14. Microclimates A microclimate is the distinctive climate of a small-scale area, such as a garden, park, valley or part of a city. The weather variables in a microclimate, such as temperature, rainfall, wind or humidity, may be subtly different to the conditions prevailing over the area as a whole... Download Fact Sheet 14 (PDF, 504 kb)

	15. Weather radar The word radar is an acronym, from RAdio Detection And Ranging. Although some primitive work on radio location had been carried out in the United Kingdom as early as 1904, it wasn't until the mid 1930s before any serious development work on radar was instigated... Download Fact Sheet 15 (PDF, 827 Kb)		16. World climates The climate of a locality is the synthesis of the day-to-day values of the meteorological elements that affect the locality. The main climatic elements are precipitation, temperature, humidity, sunshine, wind velocity... Download Fact Sheet 16 (PDF, 1.1 Mb)

	17. Weather observations Meteorological observations are made for a variety of reasons. The aim of all these observations are essentially to provide data and are a valuable source of information, which is used in a variety of different ways... Download Fact Sheet 17 (PDF, 1.85 Mb)