Water potential of the air

The water potential of the air is almost always strongly negative. The actual value can be calculated from the absolute temperature and the relative humidity.


Using the Assmann psychrometer, the wet and dry bulb temperature is determined and thus the relative humidity of the air.

In our example the appropriate values are:

Assmann psychrometer

 Water Potential of the soil water

 - 2.5 MPa

 Xylem sap pressure potential

 - 3.6 MPa

 Water Potential of the air

 - 68.4 MPa

Calculations

Mangrove Physiology Excursion Data

Will water move from the soil to the air?

Packing up at the end of the excursion!

Knowledge, like virtue, is its own reward, but a chocolate biscuit is welcome after a long day in the field!

You should now visit an actual salt marsh and mangrove stand. Some accessible ones round Sydney are listed under 'activities'. In other localities look for similarities (and differences) in the vegetation and its distribution.