© Lorem ipsum dolor sit Nulla in mollit pariatur in, est ut dolor eu eiusmod lorem 2014
Weather Glossary
Low Pressure and High Pressure Systems
Low pressure occurs where warm air ascends and cools down allowing clouds to form which is the
reason why weather is almost always unsettled when the weather is dominated by Low pressure
systems. High pressure is where cool dry air descends warming as it does so and suppressing cloud
formation leading to dry settled conditions. As you can see air flows between the two systems. Low
pressure systems have weather fronts associated with them while High pressure systems don’t. See
also Cyclogenesis and Explosive Cyclogenisis.
Below you a fax chart showing High pressure and Low pressure systems. Note the cold fronts, warm
fronts and Occluded fronts on the fax chart. Low pressure systems are indicated by L and High
pressure by H.
Picture courtesy of the Met Office
Cyclogenesis and Explosive Cyclogenesis (Bomb)
Cyclogenesis refers to the formation of low pressure systems. All Atlantic Depression, Low pressure
systems are a form of Cyclogenesis. These ranging from wave depressions to modification of ex
hurricanes. Cyclolysis refers to when the low pressure weakens soon after the cold air reaches the
centre.
Image courtesy of the http://www.britannica.com
Explosive Cyclogenesis refers to the rapid deepening of a Low pressure system where a large
pressure drop of 24 millibars in 24 hours or less. These happen quite often around the UK the best
example being the October 1987 storm once gain.
Atmospheric Pressure or Air Pressure
Atmospheric Pressure is the force per unit of on a surface by the weight of air above it. This is
commonly measured in millibars mb or Inches. So you may see a Low pressure or a High pressure
system with the number 1002 next to it.
This will be the value in millibars mb. The same value would be 29.59 in.
© Lorem ipsum dolor sit Nulla in mollit pariatur in, est ut dolor eu eiusmod lorem 2014
Weather Glossary
Low Pressure and High Pressure Systems
Low pressure occurs where warm air ascends and cools down allowing clouds to form which
is the reason why weather is almost always unsettled when the weather is dominated by
Low pressure systems. High pressure is where cool dry air descends warming as it does so
and suppressing cloud formation leading to dry settled conditions. As you can see air flows
between the two systems. Low pressure systems have weather fronts associated with them
while High pressure systems don’t. See also Cyclogenesis and Explosive Cyclogenisis.
Below you a fax chart showing High pressure and Low pressure systems. Note the cold
fronts, warm fronts and Occluded fronts on the fax chart. Low pressure systems are
indicated by L and High pressure by H.
Cyclogenesis and Explosive Cyclogenesis (Bomb)
Cyclogenesis refers to the formation of low pressure systems. All Atlantic Depression, Low
pressure systems are a form of Cyclogenesis. These ranging from wave depressions to
modification of ex hurricanes. Cyclolysis refers to when the low pressure weakens soon
after the cold air reaches the centre.
Image courtesy of the http://www.britannica.com
Atmospheric Pressure or Air Pressure
Atmospheric Pressure is the force per unit of on a surface by the weight of air above it. This
is commonly measured in millibars mb or Inches. So you may see a Low pressure or a High
pressure system with the number 1002 next to it.
This will be the value in millibars mb. The same value would be 29.59 in.
© Lorem ipsum dolor sit Nulla in mollit pariatur in, est ut
dolor eu eiusmod lorem 2014
Weather Glossary
Low Pressure and High Pressure Systems
Low pressure occurs where warm air ascends and cools down
allowing clouds to form which is the reason why weather is almost
always unsettled when the weather is dominated by Low pressure
systems. High pressure is where cool dry air descends warming as
it does so and suppressing cloud formation leading to dry settled
conditions. As you can see air flows between the two systems. Low
pressure systems have weather fronts associated with them while
High pressure systems don’t. See also Cyclogenesis and Explosive
Cyclogenisis.
Below you a fax chart showing High pressure and Low pressure
systems. Note the cold fronts, warm fronts and Occluded fronts on
the fax chart. Low pressure systems are indicated by L and High
pressure by H.
Cyclogenesis and Explosive Cyclogenesis (Bomb)
Cyclogenesis refers to the formation of low pressure systems. All
Atlantic Depression, Low pressure systems are a form of
Cyclogenesis. These ranging from wave depressions to modification
of ex hurricanes. Cyclolysis refers to when the low pressure weakens
soon after the cold air reaches the centre.
Image courtesy of the http://www.britannica.com
Atmospheric Pressure or Air Pressure
Atmospheric Pressure is the force per unit of on a surface by the
weight of air above it. This is commonly measured in millibars mb or
Inches. So you may see a Low pressure or a High pressure system
with the number 1002 next to it.
This will be the value in millibars mb. The same value would be 29.59
in.