Met Office: Frequently asked questions

	Frequently asked questions

1. Questions about the weather and forecasts
2. Units of measurement
3. Miscellaneous questions

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1. Questions about the weather and forecasts
	1.1	The weather forecast pictures don't match what's going on outside my window
	1.2	What is the weather like at .....?
	1.3	What do the weather symbols mean?
	1.4	What areas do each region cover?
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2. Units of measurement
	2.1	Why do we use Celsius rather than Fahrenheit?
	2.2	How do you convert Celsius to Fahrenheit?
	2.3	How do you convert from millibars to inches?
	2.4	What are hectopascals?
	2.5	What is UTC?
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3. Miscellaneous questions
	3.1	What are hurricanes and how are they named?
	3.2	How do I get a setting for my barometer?
	3.3	How do you define a white Christmas?
	3.4	Are any of the weather folklores correct?
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1. Questions about the weather

	1.1	The weather forecast pictures don't match what's going on outside my window. Note the answer to Q1.2. Again, read the text which is updated at 0600, 1200 and 1800.

	1.2	What is the weather like at .....? Get the latest forecast or observations from the Met Office. You can also get a detailed weather forecast via your mobile phone, including rainfall, for your location or postcode. The past weather pages also give a brief overview of the climate of various regions round the world. However, if you want detailed climate values for a specific place try World Climate. You can enter a location when prompted and this then provides long-term average values for daily maximum and overnight minimum temperatures, also rainfall, on a monthly basis. Remember that these are averages and that there can be significant variations from these figures.

	1.3	Is there a decode for the weather symbols? You can see the decode by clicking on the 'Key' link on the pages with the weather symbols.

	1.4	What areas do each region cover? There is a page which shows all the regions. It can be found by clicking on the 'Guide' link on the weather pages or by going to the guide page.

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2. Units of measurement

	2.1	Why do we use Celsius rather than Fahrenheit? The Celsius scale is the World Meteorological Organization standard for temperature measurement and is used throughout the world by the meteorological community for global exchange of information.

	2.2	How do you convert Celsius to Fahrenheit? From Celsius to Fahrenheit - F=9/5C+32 From Fahrenheit to Celsius - C=5/9(F-32) where C is the value in Celsius and F is the value in Fahrenheit.

	2.3	How do you convert from millibars to inches? Multiply the millibar value by 0.02953 to get the value in inches.

	2.4	What are hectopascals? The SI unit for pressure is a pascal. The worldwide meteorological community uses the hectopascal, i.e. a hundred pascals, which is the metric equivalent of a millibar. However, millibars (and inches) are still used in some public forecasts in the UK and USA.

	2.5	What is UTC? UTC stands for Universal Time Coordinated and it is equivalent to GMT. The Royal Observatory web site has more information on the history of timekeeping. It also has a description of local time.

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3. Miscellaneous questions

	3.1	What are hurricanes and how are they named? Many questions about hurricanes are answered on our Tropical Cyclones page.

	3.2	How do I get a setting for my barometer? Atmospheric pressure varies over time and space and also varies with height. Since the altitude of the barometer normally stays constant (the station height) a correction is made to the reading to make it equivalent to the mean sea-level reading. This is done so that readings from different locations can be compared, with differences due to height being removed. Aneroid barometers are normally adjusted to mean sea-level values - read the barometer's instructions to see how to adjust the instrument (normally by a screw on the back). Mercury barometers cannot be adjusted (don't tamper with them because a mercury spillage is a health hazard). To get the value for your barometer, choose a high-pressure day, pressure values are not changing very much - you can watch the TV forecasts for such a day. Go to the Met Office's observation page and choose the station nearest to your location - on a quiet weather day the distance away from you will not be significant. Adjust the barometer to the station's pressure value. You can check your barometer on other days but will have to compensate for fast-changing pressures or distance if the pressure is low or changing fast. The observation includes information about how the pressure is changing. There is a page on the University of Reading web site which gives more information about barometers.

	3.3	How do you define a white Christmas? See our white Christmas page for a definition and details of previous white Christmasses.

	3.4	Are any of the weather folklores correct? Some do reflect the weather conditions. You can find out the answers to this and many more queries at our Media centre.

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