simple defintiions Flashcards
what is a continuous variable
a measured variable that can take any value
what is a discrete variable
a measured variable that can only take specific values
Define population
A complete set of data where every element is included
How is daily mean temperture measured?
Values are noted in degrees (celcius) and tenths, values below 0 are preceded by a minus sign
What is the daily mean temperature?
The average of the hourly air temperature readings during the period 0900-0900 GMT
How is daily total rainfall measured?
millimetres (mm)
What is daily total rainfall?
24 hour periods commencing at 0900 GMT 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
How is daily total sunshine measured?
In hours and tenths
What is daily total sunshine?
The amount of bright sunshine recorded on the day of entry, measured by an instrument that measures the amount of solar radiation exceding a threshold
How is daily maximum relative humidity measuered?
As a percentage
What is daily maximum relative humidity?
A measure of how close the air is to being saturated with water vapour. Values greater than 95% are associtated with mist and fog
How is wind speed measured?
Knots
What is knots to mph?
1 knot = 1.15 mph
How is the daily mean wind speed measured?
Averaged over the 24 hours from 0000GMT on the date given
What is maximum gust speed?
The maximum instantaneous speed that occured during the 24 hours from 0000GMT on the date given
How is the daily mean wind direction measured?
Averaged over the 24 hours from 0000GMT on the date given, averaged to the nearest 10 degrees
How is daily maximum gust direction measured?
in degrees from true north
What is daily maximum gust direction?
The direction from which the wind was blowing when the maximum gust during the hour commencing at the time of entry occured
What is cloud cover?
The fraction of the celestial dome coverd by cloud
How is cloud cover measured?
Measured in eigths (Oktas)
What is visibility?
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 was raised to daylight level.
How is visibility measured?
Measured horizontally, values noted in decametres (Dm), a dash indicates data not available
How is pressure measured?
By the SI unit of pressure, the pascal (Pa)
Which station is the furthest north?
Leuchars
