© Lorem ipsum dolor sit Nulla in mollit pariatur in, est ut dolor eu eiusmod lorem 2014
Sheffield Weather Page

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
Sheffield Weather Page

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
Sheffield Weather Page

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 

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.