pressure.from.elevation {bigleaf} | R Documentation |

## Atmospheric Pressure from Hypsometric Equation

### Description

An estimate of mean pressure at a given elevation as predicted by the hypsometric equation.

### Usage

```
pressure.from.elevation(
elev,
Tair,
VPD = NULL,
constants = bigleaf.constants()
)
```

### Arguments

`elev` |
Elevation a.s.l. (m) |

`Tair` |
Air temperature (deg C) |

`VPD` |
Vapor pressure deficit (kPa); optional |

`constants` |
Kelvin- conversion degC to Kelvin |

### Details

Atmospheric pressure is approximated by the hypsometric equation:

`pressure = pressure_0 / (exp(g * elevation / (Rd Temp)))`

### Value

`pressure -` |
Atmospheric pressure (kPa) |

### Note

The hypsometric equation gives an estimate of the standard pressure at a given altitude. If VPD is provided, humidity correction is applied and the virtual temperature instead of air temperature is used. VPD is internally converted to specific humidity.

### References

Stull B., 1988: An Introduction to Boundary Layer Meteorology. Kluwer Academic Publishers, Dordrecht, Netherlands.

### Examples

```
# mean pressure at 500m altitude at 25 deg C and VPD of 1 kPa
pressure.from.elevation(500,Tair=25,VPD=1)
```

*bigleaf*version 0.8.2 Index]