Transcript Pressure systems and weather

How do ocean
currents impact on
climate?
Pressure systems and weather
By the end of the lesson you will;
1)
2)
3)
4)
Be able to describe and explain the weather associated with
a high and low pressure system
Be able to explain global distributions of high and low
pressure systems
Be able to explain how high and low pressure systems can
impact on the UK
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
Task
1.
2.
3.
You need to recreate the picture at the front of the classroom
You need to add in as much detail as possible
Winning groups get sweets
Describe pressure systems
Low air pressure
•
•
•
•
Warm air
Molecules further apart
Warm air rises
Molecules even further apart
LOW PRESSURE
970 – 990 Millibars (mb)
High air pressure
•
•
•
•
Cool air
Molecules closer together
Cool air falls
Molecules even closer together
HIGH PRESSURE
1020 – 1040 Millibars (mb)
Pressure systems
Task
1. Explain what a high and low pressure system is
2. Use as many of the key words as possible
3. Explain the different types of weather associated
High pressure systems have sinking air. They are associated
A high pressure system will have……….
with cold temperature in the winter, and hot temperature in
the summer. They will have clear skies and can lead to
drought.
A low pressure system will have ……..
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
Key words
Hot
Cold
Rising
Sinking
Clouds
Condensation
Rain
Sun
Clear
Drought
Flooding
Winds
Pressure systems and weather
By the end of the lesson you will;
1)
2)
3)
4)
Be able to describe and explain the weather associated with
a high and low pressure system
Be able to explain global distributions of high and low
pressure systems
Be able to explain how high and low pressure systems can
impact on the UK
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 Skies
London;, England,
Cloudy with rain, 3 degrees, low visibility
Vilankulos, Mozambique;
Sunny; 42 degrees, Cumulus clouds
Siberia, Russia;
Clear Skies, -23 degrees
Kibera, Kenya
37 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 30 degrees the air
sinks back down causing a
high pressure system
Around the equator, the air
is rising causing a low
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 weather
By the end of the lesson you will;
1)
2)
3)
4)
Be able to describe and explain the weather associated with
a high and low pressure system
Be able to explain global distributions of high and low
pressure systems
Be able to explain how high and low pressure systems can
impact on the UK
Have applied your new knowledge to an exam style question
Impacts of High and low
pressure;
Task
1. 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 weather
By the end of the lesson you will;
1)
2)
3)
4)
Be able to describe and explain the weather associated with
a high and low pressure system
Be able to explain global distributions of high and low
pressure systems
Be able to explain how high and low pressure systems can
impact on the UK
Have applied your new knowledge to an exam style question
Applying your new knowledge
Task
With reference to a named example
1. describe the causes of a low pressure system
2. Explain the impacts of this low pressure system
Level 1;
Student does not name an area
Student gives general ideas that are not linked to a specific case study
Level 2;
Student names an area
Student describes the causes of low pressure
Some 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?