This is some good reading, makes a lot of sense. Great motion diagrames that explain the difference between high and low pressures really well.
www.bom.gov.au/lam/Students_Teachers/pressure.shtmlNotice how the sinking air spirals outward in an anticlockwise direction, in the high pressure region (only in the southern hemisphere).
In the low pressure region the rising air spirals inward, in a clockwise direction (only in the southern hemisphere).
This animation shows how a small part of the air may flow across the isobars from high to low pressure.
This animation shows how air can come from other nearby pressure systems or go to other nearby pressure systems.
Definitions...
High pressure systems
The air associated with a high pressure system sinks down from above and warms as it does so and is very stable.
A high pressure system (anticyclone), is a system of closed isobars surrounding a region of relatively high pressure. When compared with low pressure systems, highs tend to cover a greater area, move more slowly and have a longer life.
When the high pressure system is located over land the weather will be typically dry and free of cloud.
Where the isobars are elongated around a high pressure system (see Figure 1) they are referred to as a ridge.
Low pressure systems
A low pressure system (cyclone) develops where relatively warm air ascends from the Earth's surface. These are systems of closed isobars surrounding a region of relatively low pressure.
As the rising air cools, clouds will begin to form. The instability of the air will produce quite large vertical development of cumuliform clouds with associated rain showers (such as cumulonimbus cloud).
An elongated extension of isobars away from a low pressure centre is known as a trough of low pressure. This trough usually contains one or more cold fronts.
Cold fronts
A cold front is the delineation between cold polar air moving towards the equator and undercutting warm tropical air moving poleward. The temperature differences across a cold front can be extreme and associated with strong winds. The warm tropical air is forced to rise and become unstable with the development of large cumuliform clouds. Severe weather such as thunderstorms, squall lines and severe turbulence may accompany these cold fronts.
On a weather chart, a cold front is represented as a line with barbs pointing in the direction of movement of the front, from cold to warmer air (see Figure 1).
Parcels of air
A parcel of air is, in essence, nothing more than a sample of air. Generally it is assumed to be small enough to be homogenous (the same all the way through). So that pressure, temperature and humidity are the same throughout it, but large enough to contain at least several thousand molecules so that these parameters are meaningful.
It is useful to visualise a blob of air. We assume that the parcel has the same pressure as its environment but also that it doesn't mix with its environment. - in other words we put it in a plastic bag that is rather too large for it.
An adiabatic process is one in which no heat is removed from, or added to, the parcel. Think of the plastic bag as being thoroughly insulated.
When a dry air parcel is lifted adiabatically, its pressure falls, and so it expands. This expansion takes place against the inwards pressure of the surrounding environmental air on the parcel.
The parcel expends energy in "pushing" the environment back.
The only source of energy available to the parcel is its temperature and so this must fall. Similarly, parcels which are forced to descend become warmer.
JB
it's amazing how it all works though!
! 
cells and Coriolis effects thrown in. This has nothing to do with the ground air temperature really 
makes it blow its good enough for me
