pvldcurve (version 1.2.6)

VaporPressureDeficit: Vapor Pressure Deficit (VPD)

Description

Calculates mole fraction vapor pressure deficit (mol * mol^-1) of the air.

Usage

VaporPressureDeficit(data, humidity = "humidity",
  temperature = "temperature", atmospheric.pressure = 101.325)

Arguments

data

data frame at least with two numeric columns of equal length containg humidity (%) and temperature (degree Celsius)

humidity

optional name of the column in data containing the humidity values; default: "humidity"

temperature

optional name of the column in data containing the temperature values; default: "temperature"

atmospheric.pressure

optional; default = 101.325 (atmospheric pressure at sea level)

Value

The original data frame extended by a numeric column with the vapor pressure deficit (mol * mol^-1).

Details

Mole fraction vapor pressure deficit is calculated as: $$(1 - RH / 100) * (VPsat / AP)$$ whereas RH = relative humidity (%), VPsat = saturation vapor pressure (kPA), AP = atmospheric pressure (kPA), whereas: $$VPsat = 0.61121 exp ((18.678 - T 234.5^-1) (T 257.14 + T))$$ where T = air temperature (degree Celsius)

Examples

# NOT RUN {
# get example data
df <- weather_data

# calculate vapor pressure deficit from weather data measured at sea level
df_with_VPD <- VaporPressureDeficit(df)

# calculate vapor pressure deficit from weather data measured at 2000 m altitude
df_with_VPD <- VaporPressureDeficit(df, atmospheric.pressure = 79.495)

# }