({{, (RefLink[UnitSystem, paclet:ref/UnitSystem]) 
is an option for functions like (RefLink[AirTemperatureData, paclet:ref/AirTemperatureData]) that determines the units of the result.}})

OpenersNotesSection(Spacer1)Details

The following settings for (RefLink[UnitSystem, paclet:ref/UnitSystem]) can be used:

Specific units depend on the function and property used.

The default setting for (RefLink[UnitSystem, paclet:ref/UnitSystem]) is determined by your (RefLink[$GeoLocation, paclet:ref/$GeoLocation]) and can be reset by adjusting (RefLink[$UnitSystem, paclet:ref/$UnitSystem]).

OpenersPrimaryExamplesSection(Spacer1)Examples  (5)

OpenersExampleSection0(Spacer1)Basic Examples  (1)

Control whether results are returned in metric or imperial units:

AirPressureData[UnitSystem->"Imperial"]

AirPressureData[UnitSystem->"Metric"]

Changing units can also be accomplished with (RefLink[UnitConvert, paclet:ref/UnitConvert]):

UnitConvert[%,"InchesOfMercury"]

OpenersExampleSection2(Spacer1)Properties & Relations  (2)

Quantities returned for station properties can be adjusted with (RefLink[UnitSystem, paclet:ref/UnitSystem]):

WindDirectionData["KCMI","Elevation",UnitSystem->"Metric"]

WindDirectionData["KCMI","Elevation",UnitSystem->"Imperial"]

The default value is determined by (RefLink[$UnitSystem, paclet:ref/$UnitSystem]), which is set by your computer's location:

OptionValue[WindSpeedData,UnitSystem]

$UnitSystem

OpenersExampleSection3(Spacer1)Possible Issues  (2)

(RefLink[WindDirectionData, paclet:ref/WindDirectionData]) does not return basic results in metric or imperial units:

WindDirectionData[UnitSystem->"Metric"]

WindDirectionData[UnitSystem->"Imperial"]

Improper settings for (RefLink[UnitSystem, paclet:ref/UnitSystem]) are ignored:

WindSpeedData[UnitSystem->"Foo"]

({{DocumentationFooterIconsRelatedFunction.png, ({{See Also}, {(RefLink[UnitConvert, paclet:ref/UnitConvert])  ▪  (RefLink[AirPressureData, paclet:ref/AirPressureData])  ▪  (RefLink[AirTemperatureData, paclet:ref/AirTemperatureData])  ▪  (RefLink[WindDirectionData, paclet:ref/WindDirectionData])  ▪  (RefLink[WindSpeedData, paclet:ref/WindSpeedData])  ▪  (RefLink[WindVectorData, paclet:ref/WindVectorData])}})}})