Ridges of high pressure are indicated by isobars extending outwards from an anticyclone. They are also sometimes referred to as ‘wedges’.  Ridges are essentially extensions of a high pressure system.  Since they are formed from a parent high pressure, their weather and characteristics are similar to a high pressure.

Closely spaced isobars imply a steep pressure gradient (common in low pressure systems) and widely spaced isobars imply a shallow pressure gradient (common in high pressure systems).  The pressure gradient produces an attractive force that will tend to pull molecules of air towards lower pressure areas.  The greater the pressure change and the greater the pressure gradient force for a given distance the faster the wind velocity.

warm air sits a few thousand feet above the surface and creates a temperature inversion commonly called a subsidence inversion,

Subsidence occurs in high pressure

QFF is The value of pressure reduced to MSL in accordance with isothermal conditions.

Isobars are line joining places of the same atmospheric pressure (usually MSL pressure QFF).

As the air descends in a high pressure system it becomes compressed.  This compression causes the air to warm and thus prevents any significant cloud from forming (because to make clouds, air must cool).  The other effect of this warming is to create a “foot” of abnormally warm air at the bottom of the high pressure system

troughs are characterised by convergence of air at the Earth’s surface, causing air to rise over a large area, producing extensive cloud with associated rain and showers

troughs are characterised by convergence of air at the Earth’s surface, causing air to rise over a large area, producing extensive cloud with associated rain and showers, in a low pressure system wind will converge and ascend &  form clouds

a low pressure system wind will converge and ascend &  form clouds

High pressure area are related to bad visibility and good weather, 

High pressure area are related to bad visibility and good weather, 

Cols are regions of almost level pressure between two highs and two lows. It is an area of stagnation.

An anticyclone or high is a region of relatively high surface pressure shown by more or less circular isobars similar to a depression but with higher pressure at the centre

above isobars are far apart  , Ridges of high pressure are indicated by isobars extending outwards from an anticyclone

In a high pressure system, air descends at the centre. As the air descends it will be heated adiabatically (more of this later) and will be warmer than the air at a lower level adjacent to the surface. This is called a Subsidence Inversion

In a high pressure system, air descends at the centre. As the air descends it will be heated adiabatically (more of this later) and will be warmer than the air at a lower level adjacent to the surface. This is called a Subsidence Inversion. Poor visibility is related to high pressure area

clouds are formed with presence of moisture and ascending air

depression large scale  low pressure area are called depression  closely packed isobars depict low pressure

If the isobars form a finger-like protrusion away from the centre of the depression an isobaric trough of low pressure is present

As air rises, the air surrounding the low pressure area will be drawn inwards in an attempt to fill the low, and return the air pressure to equilibrium.  However, the inward-moving air will experience friction as it moves over the Earth’s surface, slowing it down.  Consequently, more air leaves the divergence area in the upper atmosphere than can be replaced at the surface.  Therefore, low pressure above the warm surface is maintained, and air pressure may continue to fall over time as this process evolves.

As the storm system expands to much larger scale, the action of the Earth’s rotation becomes significant, and, unlike in the small scale low, the airflow is deflected as it is drawn towards the centre of the depression.  This deflection of the airflow can result in rotational wind speeds of up to 200 miles per hour

Blocking anticyclones are warm anticyclones formed from an extensions of high pressure areas developed in the sub- tropical regions, may hold up or divert the normal west-east passage of polar front depressions and persist for several days. In order for the anticyclone to block the passage of polar fronts it must be at higher latitudes than its parent sub tropical high. the blocking anticyclone must persist at latitudes between 45° to 65°

clouds are formed with presence of moisture and ascending air, air will converge and then ascend in low pressure system

Cols are regions of almost level pressure between two highs and two lows. It is an area of stagnation

Subsidence in high pressure can lead to fog formation , subsidence occurs in high pressure area,D is a high pressure area