How do ocean currents impact on climate?

Pressure systems and weatherBy the end of the lesson you will;

1)Be able to describe and explain the weather associated with a high and low pressure system 2)Be able to explain global distributions of high and low pressure systems 3)Be able to explain how high and low pressure systems can impact on the UK 4)Have applied your new knowledge to an exam style question

Air pressure

• Our atmosphere is made up of tiny molecules of nitrogen, oxygen, carbon dioxide and other rarer gases• These molecules have mass

and actually press down on us – this is what we call air pressure

High and low pressure

Task1.You need to recreate the picture at the front of the classroom 2.You need to add in as much detail as possible3.Winning groups get sweets

Describe pressure systemsLow air pressure

• Warm air• Molecules further apart• Warm air rises• Molecules even further apart

LOW PRESSURE970 – 990 Millibars (mb)

High air pressure

• Cool air• Molecules closer together• Cool air falls• Molecules even closer together

HIGH PRESSURE1020 – 1040 Millibars (mb)

Pressure systems

Task1.Explain what a high and low pressure system is2.Use as many of the key words as possible 3.Explain the different types of weather associated

Key words

HotColdRisingSinking Clouds Condensation Rain Sun ClearDrought Flooding Winds

A high pressure system will have……….

A low pressure system will have ……..

High pressure systems have sinking air. They are associated with cold temperature in the winter, and hot temperature in the summer. They will have clear skies and can lead to drought.

Low pressure systems will have rising air. Air rises and condenses to form clouds. This will then lead to large amounts of rain. If over a long period of time, there will be flooding. There can also be wind that is associated with a low pressure system

Pressure systems and weatherBy the end of the lesson you will;

1)Be able to describe and explain the weather associated with a high and low pressure system 2)Be able to explain global distributions of high and low pressure systems 3)Be able to explain how high and low pressure systems can impact on the UK 4)Have applied your new knowledge to an exam style question

What type of pressure system do you think

each city has in the forecast? Cape Town, South Africa; Sunny, 25 degrees, Clear SkiesLondon;, England, Cloudy with rain, 3 degrees, low visibilityVilankulos, Mozambique; Sunny; 42 degrees, Cumulus clouds Siberia, Russia; Clear Skies, -23 degreesKibera, Kenya37 degrees, cumulo-Nimbus Clouds, heavy rain showers.

Using your white boards, decide if each city is experiencing high or low pressure

How are pressure systems formed and distributed?

Atmosphere is cooled in the polar regions. Cold air sinks forming an area of high pressure

Between 35N and 65N mixture of high and low pressure belts moving from west to east. Makes weather very changeable

Around the equator, the air is rising causing a low pressure system

Around 30 degrees the air sinks back down causing a high pressure system

Task; Study the information

1.What weather will be associated at 0, 30, 60 and 90 degrees? 2.How does the weather affect the features found at 30 degrees? 3.What weather system are we in the UK affected by?

Pressure systems and weatherBy the end of the lesson you will;

1)Be able to describe and explain the weather associated with a high and low pressure system 2)Be able to explain global distributions of high and low pressure systems 3)Be able to explain how high and low pressure systems can impact on the UK 4)Have applied your new knowledge to an exam style question

Impacts of High and low pressure; Task1.Each of you has an article on one pressure system 2.You need to make notes 3.Be ready to teach the rest of the class

Social Impacts Economic Impacts Environmental impacts

Low pressure system

High pressure system

Extension; How might the impacts of low pressure systems be reduced in the future?

So what are high pressure systems and how do they impact the UK?• High pressure systems are called Anticyclones• Bring high pressure and settled conditions lasting for

days or weeks• Clear skies – VERY FEW CLOUDS• In summer they are associated with clear warm weather• In winter they bring clear, bright, cold days. As heat is

lost at night, the mornings are cold and frosty.• Isobars in a high pressure system increase in value

towards the centre

Key Word; Isobars are lines on a map which indicate areas of similar pressure

Depressions

• Depressions bring areas of low pressure which usually bring rain and cloud and wind to the British Isles.

• They usually develop to the west of the British Isles over the Atlantic ocean

• Warm moist air from the South meeting colder drier polar air from the North.

• 2 air masses because they are different densities cannot mix and so the warm less dense air is forced to rise over the cold denser air.

NICE and easy; “when the weather is not very nice we get really depressed.”

• Clip of a depression

Pressure systems and weatherBy the end of the lesson you will;

1)Be able to describe and explain the weather associated with a high and low pressure system 2)Be able to explain global distributions of high and low pressure systems 3)Be able to explain how high and low pressure systems can impact on the UK 4)Have applied your new knowledge to an exam style question

Applying your new knowledge

TaskWith reference to a named example1.describe the causes of a low pressure system2.Explain the impacts of this low pressure system

Level 1; Student does not name an areaStudent gives general ideas that are not linked to a specific case study

Level 2; Student names an areaStudent describes the causes of low pressureSome impacts are added in but lacking in detail

Level 3; Student describes the cause of low pressure Geographical terminology added in Student uses a minimum of 3 figures in their answer Impacts are divided into Social / economic/ environmental

What have you learnt?