Transcript Weather - Glow Blogs

Weather
What is the difference
between weather and climate?
Weather and Climate
Weather
The condition of our atmosphere. This is made
up of temperature, rainfall, wind speed and
other elements which change all the time.
Climate
The average temperature, rainfall and wind
speed in one place. Climate varies across the UK.
Copy these points down.
Weather
Factors affecting
temperature and rainfall in
the UK
Q. What 4 factors affect
temperature in the UK?
Discuss this in your groups and try and
identify all 4 factors.
What 4 factors affect temperature
in the UK?
1. Latitude
2. Aspect
3. Relief (the shape of the land)
4. Distance from the sea
1. Latitude
• Further from the equator the sun’s rays are at a lower
angle and pass through more atmosphere. They lose
heat among the clouds, gas and dust.
• The rays spread out over a wider area so there is less
heat.
2.Aspect
Aspect is the direction which the land faces. Places
facing south are warmer because:
1. They receive more heat from the sun.
2. They are sheltered from cold northerly winds.
3. Relief
Temperature decreases by 1°C for every 150
metres in height
4. Distance from the sea
In winter it is warmer in the west of the UK because:
1. The Atlantic is milder than the land surface because
water cools more slowly than land.
2. The North Atlantic Drift (a warm ocean current) makes
it even milder.
3. Our prevailing winds come from the south-west and bring
warmth from the Atlantic.
What 3 factors affect rainfall in
the UK?
Discuss this in your groups and try and identify
3 factors that affect rainfall.
1. Relief (the shape of the land)
2. Aspect
3. Distance from the sea
1. Relief
 In pairs identify the link between relief (shape of
the land) and rainfall in the UK.
Upland areas receive more
rain than lowland areas
because:
1. Moist air blows in from
the Atlantic.
2. The air rises over the
hills and cools down.
3. As the air cools the water
vapour condenses into
water droplets.
4. The water droplets come
together to form clouds.
5. The droplets become
bigger and fall as rain.
Relief
2. Aspect
West facing slopes receive the most rain as the
Atlantic is to the west of the UK.
Areas to the east are in the rain shadow and have
less rain as the air is drier
3. Distance from the sea
Winds in the west
are full of water
vapour and bring a
lot of rain.
As the winds move
eastwards they drop
most of their water
and become drier.
Re-cap
1. Latitude
2. Aspect
3. Relief
4. Distance from the sea
Weather activity
You are going to produce an information sheet about the
factors that affect temperature and rainfall in the UK.
On the information sheet you must include information on the
following:
1. How latitude affects temperature
2. How aspect affects both temperature and rainfall
3. How relief affects both temperature and rainfall
4.How distance from the sea affects both temperature and
rainfall
The information sheet must be easy to read, well organised
and if possible, use images.
Air masses
Air masses
• There are five different air masses
which affect the UK:– Polar maritime (Pm)
– Polar continental (Pc)
– Tropical maritime (Tm)
– Tropical continental (Tc)
– Arctic maritime (Am)
Air masses
Air masses
• Continental masses – come from a large
land mass like Europe or Africa.
• Maritime masses – come from a large
ocean like the Atlantic or Arctic.
• Tropical masses – originate in warmer
areas like North Africa or the
Caribbean.
• Polar and Arctic masses – start in very
cold areas like Siberia or the Arctic.
Air masses
Comes from Norway
and Greenland. Very
cold, wet weather.
Snow in winter,
showers in summer.
Cold, biting winds.
Comes from
North Atlantic
Ocean. Cool, wet
and dull weather.
Strong winds. Our
most common air
mass.
Comes from tropical
Atlantic Ocean.
Warm and wet
weather in summer.
Mild and wet
weather in winter.
Strong, south west
winds.
Comes from
Siberia.
Very cold,
dry weather
in winter.
Warm, dry
weather in
summer.
Very little
wind.
Am
Pc
Pm
Tc
Tm
Comes from
Sahara
desert. Hot
and dry in
summer.
Light winds.
Q. Which air masses will these
people want the most and why?
a)
b)
c)
d)
e)
marathon runners
people working in emergency services
travel agents
farmers
white water rafters
Air pressure
systems
Air pressure systems
The Earth’s surface
is warmed by the sun’s rays.
Air pressure systems
• There are two main types of air
pressure systems:– High pressure systems
– Low pressure systems
• High pressure – when air is cold and
heavy and is pressing down on the
surface.
• Low pressure – when air is warm and
light and rises up into the upper
atmosphere.
Air pressure systems
• Low pressure systems:– Are called depressions or cyclones.
– Spin in an anti-clockwise direction.
Low
Air pressure systems
• High pressure systems:– Are called anti-cyclones.
– Spin slowly in a clockwise direction.
High
Air pressure systems - weather
• Watch the clip about ‘High and low
pressure’ – be ready to complete the table
whilst watching the clip.
– http://www.bbc.co.uk/learningzone/clips/highand-low-pressure/3240.html
Air pressure systems
High pressure
Low pressure
Proper name
Anti-cyclone
Depression
Pressure
reading
Over 1000mb
1000mb or less
Little or none
A lot – 5 oktas or more
Cloud cover
Sunshine
Much
Little/none
Little or calm
Spins clockwise
windy
Spins anti-clockwise
Precipitation
Hardly any/none
Increasing amounts
Temperature
Winter very cold/
Summer hot
Other
weather
Winter - freezing
fog, hard frost.
Summer – heat wave
Wind speed
Winter cold or
cool/Summer cool
Stormy
Weather fronts
Depressions
Air pressure systems -
Depressions
• Watch the clip about ‘Depressions and
frontal rainfall in the UK’.
– http://www.bbc.co.uk/learningzone/clips/depressions-andfrontal-rainfall-in-the-uk/3090.html
Low pressure systems
Imagine an area out in the North Atlantic
Ocean, to the West of the UK where the air is
fairly cool.
This cool air is represented by the light blue
background on the following slides.
Cold air will be shown in darker blue.
Warm air will be shown in red.
The air masses over the Atlantic
Two air masses meet:
1. Cold Arctic air blowing from the North East
2. Warm moist Tropical air blowing from
the South West
The air masses meet……
Cold Arctic air
blows from the
North East
Warm, moist Tropical
air blows from the
South West
……But they do not mix
The two sets of air do
not mix together
As they blow past each
other, friction causes
them to swirl round
Warm and cold sectors
The cold area is called
the COLD SECTOR.
Cold Arctic
air
Warm,
moist
Tropical
air
The warm area is
called the WARM
SECTOR.
Direction of movement
These systems usually move
either East, or North East
Cold Arctic
Cold Arctic
Cold ArcticCold Arctic Cold Arctic
Cold Arctic
air
air
air
air
air
air
Warm, Warm,
moist moist
TropicalTropical
air
air
Warm,
moist
Tropical
air
Warm,
moist
Tropical
air
Warm,
moist
Tropical
air
Warm,
moist
Tropical
air
Warm and cold fronts
The line between the
warm sector and the
cold sector is called
the COLD FRONT.
Cold Arctic
air
Cool
air
Warm,
moist
Tropical air
The line between the
cooler air and the warm
sector is called the
WARM FRONT.
Warm front
• The symbol below is used on a synoptic
chart to represent a warm front:-
Half circles are
used to represent a
warm front.
Cold front
• The symbol below is used on a synoptic
chart to represent a cold front:-
Triangles are used
to represent a cold
front.
Depressions
 Clearly label your synoptic chart with the following:
Isobars – lines joining places with the same air pressure
Windspeed – isobars close together show strong
winds; isobars wide apart show gentle winds
1004 – unit of air pressure, in millibars (mb)
Wind direction – winds blow anticlockwise
around and towards the low pressure
Cold front – cold air undercuts
warm air
Warm front – warm
air rises over cold air
Air pressure systems –
Depressions
Copy the diagram below into your jotter, on a full page,
leaving space underneath to write notes. Colour it in if
you get time.
Stage 5:
Heavy rain
stops, air
pressure
rises, fewer
clouds,
temp drops,
winds ease.
Stage 4:
Heavy
cloud,
heavy rain,
cold front
passes.
Strong W
winds.
Stage 3:
Sky
clears,
rain
stops,
warmer
and some
showers.
Stage 2:
Clouds
thicken,
air
pressure
falls,
steady
rain. SW
winds
Stage 1:
A few high
clouds,
dry and
temp
rises.
Steady rain at warm frontAs the warm air slowly rises it
Depression:
cools, its water content
condenses and clouds form
Rainfall
(nimbostratus then altostratus).
The result is steady rain, later
giving way to drizzle and finally
clearer skies with
high cirrus clouds.
Heavy rain at cold frontThe cold air pushes the warm
air upwards more violently at
the cold front, where the air
cools and condenses producing
deeper clouds and heavier
rainfall (cumulonimbus,
then cumulus). The result is
heavy rain or thunderstorms.
Depression:
Rainfall
Air pressure systems - Depressions
• Watch the clip about ‘Weather fronts’ – be
ready to complete an exercise about it after.
– http://www.bbc.co.uk/learningzone/clips/w
eather-fronts/3241.html
What happens at the warm front?
The first sign of an approaching warm front is CIRRUS
cloud
Warm air begins to rise over the cooler air
As air rises, it begins to cool
Cool air can hold less water vapour than warm air
Water vapour begins to condense into water droplets
Water droplets begin to form clouds
NIMBOSTRATUS clouds bring prolonged rain at the
warm front
What happens at the cold front?
The cold Arctic air moves faster than the warm air
The cold Arctic air is denser than the warm air
The cold Arctic air undercuts the warm air, forcing it up
quickly
Water vapour begins to condense into water droplets
Water droplets begin to form very tall clouds
The clouds along the cold front are called
CUMULONIMBUS
CUMULONIMBUS – give very heavy showers, sometimes
with thunder and lightning
The passage of a depression
Occluded front
• The symbol below is used on a weather
chart/forecast to represent an occluded
front:Half circles and
triangles are both
shown together to
represent an occluded
front.
Occluded front
• Eventually the cold front catches up
with the warm front forming an
occluded front:– All the warm air is pushed up and away.
– Both sets of rain from the warm front
and cold front occur.
Now do the activities
from the booklet
Practice question
Using what you have learnt about
depressions do the question in the
booklet about the yacht race in northern
Scotland.
Yacht race question
High Pressure (Anti-cyclones)
Anti-cyclones
• In pairs – write down as many weather
conditions as you can see for each
picture.
Summer
Winter
Anti-cyclones
• An anti-cyclone is an area of high
pressure which brings long periods of
settled weather. Warm air is sinking
which means clouds do not form.
High Pressure
High Pressure
1.
2.
3.
4.
5.
6.
Anti cyclones are areas of high pressure
In high pressure areas the air is sinking
Because the air is sinking no air is rising and cooling
Because no air is rising there are few clouds and no rain
Because there is little rain there is plenty of sunshine
Because there is a lot of sunshine weather is hot in
summer
7. Because there are few clouds it is very cold at night
8. Because it is hot in summer there may be thunderstorms
9. Because anti-cyclones move slowly the weather is settled
10.Because the isobars are widely spaced winds are very
light
Impacts of pressure systems
• In your groups explain the positives and
negatives of depressions and anti-cyclones on
the sheets in your tables.
• You will have 2 minutes per sheet and then
you will move on.
Depressions
Positives
Negatives
Reliable water supply for
reservoirs supplying drinking
water.
Replenishes ground water so
droughts are less likely in summer.
Strong winds can cause power
cuts, trees can block roads and
disrupt travel.
Flooding can ruin homes and
costs money to repair.
Water for crops to grow (wheat,
peas) and animals (cows, sheep)
to drink.
Airports can be closed resulting in
delays.
Reliable winds can turn turbines
and make electricity.
Sports events/festivals can be
cancelled.
Water can fill reservoirs to make
hydro electric power.
Less tourism can result in less
profit for businesses
Anti-cyclones
Positives
Negatives
More tourist visits bring in money to Water shortages can kill crops and
hotels, ice cream shops, sales of BBQ hosepipe bans are put in place.
food.
Worth £12 billion and employs
210,000 people in Scotland.
Forest fires can kill wildlife and roads
can break up in the sun’s heat.
In winter ski resorts make more
money.
People can get heat stroke and
sunburn and have to go to hospital.
Frosts kill pests in the soil so farmers
don’t have to use as much pesticide.
In winter snowfall means money is
lost as people cannot get to work.
People can be more active outdoors
which makes people happier.
Road accidents can kill people and
old people can die in the cold so the
government pays for winter fuel
payments
Forecasting
• There are a few ways in which we can
receive a weather forecast:



Internet/phone
Television
Radio
Newspaper
How do we collect weather information?
Met Office supercomputer
Cost - £30 million
Power – equivalent to 100,000 PCs
Speed – can carry out 1000 billion calculations per second
Energy – uses 1.2 megawatts (1,200,000 watts) of energy –
enough to power 3 or 4 Balfron villages
Weather
station
circles
When forecasting the weather certain weather
symbols are used to help us understand the type of
weather expected.
Weather station circles
• Describe and explain what the two weather symbols
below are showing:7
A
B
-4
• A – cloud cover 8 oktas, Southerly wind (wind coming
from the South) at 50 knots or more, temperature 7
°C, showers.
• B – cloud cover 1 okta, Easterly wind (wind coming
from the East) at 10 knots, temperature -4 °C, clear
skies and sunshine.
Weather symbols
F
D
C
Match the statements
to the correct
letter/s.
Overcast
Wind speed 18-22 mph
Low Pressure
High Pressure
Clear Sky
E
A
G
B
Drizzle
Rain Shower
Northerly winds
North westerly winds
Wind speed 8-12 mph
Activity
Get your homework question out and
peer mark your neighbours to see how
they did.
Remember it is out of 6 marks, where
do you think the marks are coming
from?
How could they improve their answer?
Explain the
changes
which will
take place in
the weather
in Glasgow
over the
next
24 hours.
6 marks
Explain Question
Give reasons for the
changes to Glasgow.
EXPLAIN!!!
Remember that a
depression only takes 1-3
days to pass over
dependent on the wind
speed.
Explain Question
Use the stages of the depression to answer
this:
It is a 6 mark question and there are only 5
stages of the depression so we get the
other mark from describing the weather in
Glasgow currently.
Stage 5:
Heavy rain
stops, air
pressure
rises, fewer
clouds,
temp drops,
winds ease.
Stage 4:
Heavy
cloud,
heavy rain,
cold front
passes.
Strong
winds.
Stage 3:
Sky
clears,
rain stops,
warmer
and some
showers.
Stage 2:
Clouds
thicken,
air
pressure
falls,
steady
rain.
Stage 1:
A few
high
clouds,
dry and
temp
rises.
1.The weather in Glasgow currently is:
The depression has not yet reached Glasgow
and therefore is currently in the cold sector
where we find cold temperatures, calm wind
speeds as the isobars are not close together
with clear skies because there are no fronts
nearby at this time.
2nd Mark Now you are going to explain
the 1st stage in the depression.
Within the next 24 hours Glasgow
will experience a range of weather
as a result of the fronts the
depression brings. The first stage
is before the warm front comes
where there a few high clouds in
the sky, such as Cirrus clouds, the
weather is dry and the
temperature begins to rise as the
warm air is beginning to arrive in
Glasgow.
3rd mark will come from 2nd stage
The next stage is where the
clouds begin to thicken and the
air pressure falls. This stage is
where we find steady rainfall as
the warm air slowly rises it cools,
its water content condenses and
clouds form and results in the
steady rainfall. The temperature
is still warm as it is the warm
front passing.
4th Mark will come from stage 3.
Stage 3 is in the warm
sector where the sky clears
and the steady rain stops
and turns to drizzle as the
warm air has now risen and
the air pressure is steady.
The temperature is warmer
as a result of the warm
sector position.
5th mark from stage 4.
Stage 4 is where we find deeper
cloud and heavy rain fall as the
cold front pass with strong wind
speeds as the isobars are packed
closely together. The rainfall is
heavier here due to the cold air
pushes the warm air upwards
more violently at the cold front,
where the air cools and
condenses (cumulonimbus,
then cumulus).
6th Mark coming from stage 5.
Stage 5 is the final stage of a
depression where the heavy rain
stops as the cold front is no
longer overhead and the air
pressure rises. This leads to
fewer clouds with a temperature
decrease as a result of the cold
sector. The wind speeds ease
with the isobars being further
apart.
a. condition of our atmosphere. This is made up
of temperature, rainfall, wind speed and other
2. Weather elements which change all the time.
b. an area of high pressure which brings long
3. Depression periods of settled weather. Warm air is sinking
which means clouds do not form.
c. areas of low atmospheric pressure which
4.
Anticyclone produce cloudy, rainy and windy weather.
d. transition zone where a warm air mass is
5. Weather replacing a cold air mass.
Station Circlee. the leading edge of a cooler mass of air,
replacing (at ground level) a warmer mass of air
6. Cold Front f. a prediction of what the weather will be like in
an hour, tomorrow, or next week.
g. the average temperature, rainfall and wind
7. Warm
speed in one place.
Front
h. symbolic illustration showing the weather
8. Forecast occurring at a given reporting station.
1. Climate
Yacht Race Question
Where are we getting our marks from?
An 8am Boat Race from Wick to
Stornoway was cancelled, why?
0700 h
31 August
Where?
Wick and Stornoway
Direction?
From Wick to Stornoway
When?
Race due to start at 0800h
Map is for 0700h
Study the map for information
Occluded front:
broad belt of
very heavy rain,
low cloud and
poor visibility.
Cold mP air
South
westerly
winds
Associated
weather is
moving
west to
east
Warm mT air
Centre of
low pressure
: likely to
bring stormy
weather
Tightly
packed
isobars :
strong
winds
Back to the question ….
Why was the race cancelled?
• Competitors would risk very strong winds and
•
•
•
•
therefore high seas
They would be sailing straight into the wind so
it would be difficult to make progress
Temperatures would be low
There would be heavy rain
There would be thick cloud and probably poor
visibility
But this is not enough. Why not?
“Explain.. With reference to the map”
•
•
•
•
•
Strong winds – close isobars
Head winds – wind direction SW
Low temperatures – Pm air mass
Heavy rain – occluded front
Low cloud and poor visibility – occluded front
5 marks