Large Data Set

Question 1

What are the different locations data is taken from?

Answer 1

• 5 UK weather stations:
  (From north to south) -> Leuchars, Leeming, Heathrow, Hurn, Camborne
• 3 oversees
  (From west to east) Jacksonville (Florida) , Beijing (China) and Perth (Australia)

Question 2

What are the time periods that the data is taken from?

Answer 2

• May to October 1987 (6 months)
• May to October 2015 (6 months)

Question 3

Which months classify for each season?

Answer 3

• May / June are at the end of spring
• July - September is summer
• October is autumn

Perth (Australia) is in the southern hemisphere, so July- September is winter.

Question 4

What are some key dates ?

Answer 4

• UK Great Storm The night of 15-16th October 1987 gusts up to 100 knots were recorded
• In Florida:
  Hurricane Floyd -> 12th October 1987
  Hurricane Joaquin -> 1-2 October 2015

Question 5

What are the variables records?

Answer 5

• Daily Maximum Temperature
• Daily Total Rainfall
• Daily total sunshine
• Daily maximum relative humidity
• Daily mean wind speed; Daily maximum Gust
• Daily Mean Wind direction; Daily Maximum Gust direction
• Cloud cover
• Visibility
• Pressure
• n/a
• trace

Question 6

Information about Daily Maximum Temperature

Answer 6

• Air temperatures are recorded by thermometers in a louvered screen 1.25 metres above short grass, except at some Weather Centre’s and Climate Data Logger stations, where observations are made from a non-standard roof top exposure.
• Values are noted in degrees and tenths (Degrees Celsius) and values below 0 Deg C are preceded by a minus sign. A reading which is not available is listed as ‘n/a’.
• The daily mean air temperature (0900-0900 GMT) is the average of the hourly temperature readings during this period.
• Normally between 8-19 degrees Celsius

Question 7

Information about Daily Rainfall

Answer 7

• Daily totals refer to 24 hour periods commencing at 0900 Greenwich Mean Time (1000 British Summer Time) on the day of entry and includes any solid precipitation, such as snow or hail, which is melted and measured in the same way as rainfall.
• A ‘trace or tr’ of rain is an amount less than 0.05mm. A reading which is not available will be shown by ‘n/a’.
• All totals are in millimetres (mm).
• Normally below ten but can go higher to 40s

Question 8

Information about Daily Total Sunshine

Answer 8

• At most Met Office stations sunshine is measured by an instrument that measures the amount of solar radiation exceeding a threshold.
• Sunshine amounts are recorded in hours and tenths and show the amount of bright sunshine recorded on the day of entry.
• A reading which is not available is listed as ‘n/a’.
• Normally between 0 and 15

Question 9

Information about Daily Maximum Relative Humidity

Answer 9

• The relative humidity is a measure of how close the air is to being saturated with water vapour.
• Relative humidities of above 95% are associated with mist and fog.
• A reading which is not available is listed as ‘n/a’.
• Normally between 80-100%

Question 10

Information about Daily Mean windspeed, Daily Maximum Gust, Daily Mean Wind Direction and Daily Maximum Gust Direction

Answer 10

• Wind speeds are given in knots (1 knot = 1.15mph).
• The daily mean speed is averaged over the 24 hours from 0000GMT on the date given.
• Normally around 0-21
• The maximum gust speed is the maximum instantaneous speed that occurred during the 24 hours from 0000GMT on the date given. Readings for both variables which are not available are listed as ‘n/a’.
• Normally around 9 to 78
• The ​daily mean wind direction is averaged over the 24 hours from 0000GMT on the date given, ​rounded to the nearest 10 degrees
• The direction of the maximum gust is that direction from which the wind was blowing when the maximum gust during the hour commencing at the time of entry occurred, and is measured in degrees from true north.
• For all locations, the speed of the wind is also categorised according to the Beaufort scale. For the UK locations, the wind and gust direction measurements are also listed as cardinal directions.

Question 11

Information about cloud cover

Answer 11

• Cloud cover is measured in eighths (Oktas).
• Cloud cover is the fraction of the celestial dome covered by cloud.
• Eights of the sky covered by cloud
• Discrete
• 0 would mean a clear sky and 8 would mean completely overcast.

Question 12

Information about visibility

Answer 12

• Visibility is defined as the greatest distance at which an object can be seen and recognized in daylight, or at night could be seen and recognized if the general illumination were raised to daylight level.
• It is measured using visiometer at automatic sites but used to be done by observers at manual stations except at some Weather Centres and Climate Data Logger stations, where observations are made from a non-standard roof top exposure.
• Visibility is measured horizontally.
• Values are noted in decametres (dam). 1 Dm = 10m
• A dash indicates data not available.
• Normally between 0 to 60,000

Question 13

Information about pressure

Answer 13

• The mean sea level pressure has been calculated from a measurement made at station level.
• Units - the pressure unit used in meteorology was previously the millibar (one bar = 1000 millibars). However, this has been replaced by the SI unit of pressure — the pascal (Pa).
One hectopascal (hPa) = 1 millibar (mb).
- Normally between 990-1040

Question 14

What is the Beaufort Scale?

Answer 14

• To measure Windspeed
• Discrete scale with 13 values where 0 is <1Kn and 12 is a hurricane