When you hear the word thickness you usually are talking about a layer.
You can also describe our atmosphere's thickness. So how do we do that?
A horizontal thermal gradient creates a PGF at upper levels. As you increase in altitude,
the pressure gradient between the warm column and the cool column increase. Last week we saw that
wind in geostrophic balance, balances
the PGF and Coriolis force. As the PGF increases the magnitude of the wind will increase and so will the Coriolis force.
In this figure, the size of the green circles represent the magnitude of the geostrophic wind and the x in the circle
represents the tail end of the directional arrow, so we are looking at an arrow pointing into away from us.
The thermal wind describes the vertical geostrophic wind shear. So how do we define it?
The direction of the Thermal wind will tell us about the thermal structure of the atmosphere. The thermal wind always is point parallel to lines of constant thickness with lower thicknesses to the left, therefore, the thermal wind will always have the colder air to the left. So what does this tell us about the veering and backing winds?
This is the case of Veering wind we saw before. If colder air is always to the left, then we have
Warm Air advection
This is the case of backing wind we saw before. If colder air is always to the left, then we have
Cold Air advection