Download WEATHER

NATIONAL 4 AND 5
GEOGRAPHY
ST. ANDREW’S HIGH SCHOOL
MRS CARRUTHERS, MISS CURLEY AND MS LYNAS
CHECKLIST – WHAT DO I NEED TO KNOW?
•
What will I learn?
•What factors affect temperature
•What factors affect precipitation
•How to read synoptic symbols
•How to read a synoptic weather chart and base forecasts on it
•What the main air masses affecting the UK are
•What type of weather we associate with a cold front, warm front
and depressions
•How wind speed and direction is connected to isobar patterns
•What type of weather we associate with anticyclones
INTRODUCTION
Precipitation
Cloud
Cover
Visibility
WEATHER
Humidity
ELEMENTS
Air
Pressure
Wind
Speed
Sunshine
1. LATITUDE (how far North or South you are from the
Equator)
- Places closer to the equator are warmer
- The further North or South you travel the colder it gets
- This is because the Sun’s energy is concentrated at the equator
- The distance that energy travels through the atmosphere is less at the equator so
less heat is reflected by clouds, gas and dust
- The equator is green and absorbs the sun’s energy but the poles are white and
reflect the sun’s energy
2. ALTITUDE (how high up you are)
- The higher up you go the colder it gets
- E.g. as you climb a mountain the temperature drops
- Wind speed also increases at altitude
- Rain is common higher up as warm air is forced to
rise and starts to condense
3. ASPECT
- In the Northern Hemisphere, north facing slopes make good ski runs as
they receive little sunlight during the day
- South facing properties often have conservatories as they receive a lot
of sunlight during the day.
- South facing slopes are better for growing crops on
-In the Southern hemisphere the opposite would be true
- In the UK, West facing slopes receive more rain because the Atlantic
4.
DISTANCE FROM THE SEA
•
Distance from the sea affects temperature.
•
In summer places which are inland are
usually warmer than places near the coast.
•
In winter, inland places are colder than places
near the coast.
•
Distance from the sea affects temperature
since the sea takes longer to heat up than the
land.
•
Once warm, however, the sea keeps its heat
for longer.
4.
DISTANCE FROM THE SEA (continued)
•
In summer, the sea is cooler than the land and coastal regions are
cooled by sea air.
•
In winter, the sea is warmer than the land and coastal regions are
warmed by sea air.
•
Inland areas are away from the influence of sea air.
•
Inland areas get very hot in summer.
•
Inland areas get very cold in winter.
COASTAL AREA COOLED BY SEA BREEZE ON A
SUMMER’S DAY
COASTAL AREA WARMED BY SEA BREEZE
ON A WINTER’S DAY
MAIN AIR MASSES AFFECTING THE UK
QUICK SUMMARY OF AIR MASSES
Area air mass has come from
Weather characteristics
Arctic
Cold
Tropics
Warm
Land
Dry
Water
Wet
AIR MASS
WHERE IT
CAME FROM
WINTER
WEATHER
CONDITIONS
SUMMER
WEATHER
CONDITIONS
Arctic Maritime
Arctic Ocean
Very cold and
snow
Cold and wet
Polar Continental
Northern Europe
and Siberia in
Russia
Very cold and dry
Hot, dry and sunny
Polar Maritime
North Atlantic
Ocean
Cool, cloudy and
rain showers
Cool, cloudy and
rain showers
Tropical
Continental
Northern Africa
and Southern
Europe
Mild, dry and sunny
Very hot, dry and
sunny
Tropical Maritime
South Atlantic
Mild and wet
Warm and wet
2014 N5 EXAM QUESTION
Describe how a prolonged spell
with a tropical continental air
mass in summer would affect the
people of the British Isles?
(3 marks)
MARKING SCHEME ANSWER
•
A tropical continental air mass will bring hot dry weather in
summer which could result in droughts (1);
•
there might need to be hosepipe bans (1);
•
grass might wither and die causing problems for livestock
farmers (1);
•
ice cream sales might rise (1) as people make the most of
the sunny weather and head for the beach (1);
•
it could be very hot and difficult to do physical work outside
(1); heavy rain from thunderstorms might cause flash floods
(1).
Weather
station circles
LETS TRY TO MAKE
YOUR OWN WEATHER
STATION CIRCLES
A
B
Temperature
14 C
Temperature
3C
Wind Speed
10 knots
Wind Speed
25 knots
Wind
Direction
West
Wind Direction North
Weather
Rain
Weather
Snow
Cloud Cover
6 Oktas
Cloud Cover
8 Oktas
C
D
Temperature 22 C
Temperature
-5C
Wind Speed
15 knots
Wind Speed
Calm
Wind
Direction
South West
Wind Direction
Weather
Drizzle
Weather
Fog
Cloud Cover
Sky Obscured
Cloud Cover 8 Oktas
What happens at fronts?
A warm front means that warm air is coming.
At a warm front, warm air is rising over cold air.
This usually produces clouds and rain.
A cold front means that cold air is coming.
At a cold front, cold air pushes under the
warm air.
This produces strong winds and heavy rain.
LOW pressure is when air is light
and rises up into the upper
atmosphere.
HIGH pressure is when air is heavy
and is pressing down on the
surface.
Warm air rising
causes LOW
pressure.
Cold air falling
causes HIGH
pressure.
wind
The Earth’s surface
is warmed by the sun’s rays.
AIR PRESSURE SYSTEMS
AIR PRESSURE SYSTEMS
Low pressure systems
(less than 1000mb) are
called DEPRESSIONS.
They spin in an anticlockwise direction.
Low
High
High pressure systems
(more than 1000mb)
are called
ANTICYCLONES and
they spin slowly in a
clockwise direction.
Each of these systems brings different weather!
Passage of a Depression
This is a satellite
photograph of a
depression. Note the
swirling pattern of white
clouds.
The dark is the sea below
the system.
LOW Pressure is also known as a DEPRESSION
Cold Sector
Warm Sector
Depressions are made up of different air masses.
Where these air masses meet is known as a ‘front’.
When depressions move, the weather changes.
Describing and Explaining DEPRESSIONS
NOTE:
Explaining weather in a depression is very difficult. The following sentence
enders should help:
…as warm air is forced to rise over cold air, condensing and forming clouds
…as there is warm/cold air overhead
…as the isobars are close together
Passage of a Depression
COLD SECTOR
WEATHER
Temperature starts to
decrease because there is
cold air overhead.
Air pressure starts to
increase.
Green Text = Describe
Red Text = Explain
AT THE COLD FRONT
Cumulonimbus clouds
Heavy rain/ thunderstorms
because warm air is forced to rise
over cold air as it is less
dense.
Warm air starts to condense and
form as clouds leading to rain.
The rain here is heavier than the
warm front due to the gradient
between the two air masses.
Wind speed starts to increase
IN THE WARM SECTOR
WARM FRONT
Stratus clouds
Cirrus clouds can be seen high
in the sky
Temperature starts to
increase because there
is warm air overhead.
Rain begins because warm air
is forced to rise over cold air as
it is less dense.
Rain showers
Warm air starts to condense
and form as clouds leading to
rain.
Wind speed starts to
increase because
isobars are closer
together
Air pressure drops as
warm air is rising.
HIGH Pressure is also known as an ANTICYCLONE
There are no ‘fronts’ in an Anticyclone – it is just one air mass.
Differences between SUMMER and WINTER ANTICYCLONES
HIGH PRESSURE
 Anticyclones
 Pressure increases towards
the centre
 Isobars are widely spaced
 Light winds
 Winds move in a clockwise
direction
 Little cloud
 Dry
LOW PRESSURE
 Depressions
 Lowest pressure in the
centre
 Isobars are close together
 Strong winds
 Winds move in an anticlockwise direction
 Warm and cold fronts
 Unsettled weather
 Rain at the fronts
 Cloudy skies
HOW TO ANSWER A POPULAR
WEATHER QUESTION
SIMILAR TO NATIONAL 5
2014 EXAM QUESTION
PAY ATTENTION TO THE STRUCTURE
Synoptic Chart for
the British Isles at
0700h on 31
August
A yacht race from Wick to
Stornoway was due to start from
Wick harbour at 8.00am on 31
August
At 7.00am the Met Office
advised the race organisers to
cancel the race.
With reference to the synoptic
chart, explain why this advice
was given.
5 marks
WHAT ARE THE KEY WORDS?
type of boat : think!
place : see map
A yacht race from Wick to
Stornoway was due to start
from Wick harbour at
time : compare 8.00am on 31 August
direction : see
map
with map
At 7.00am the Met Office
advised the race organisers
to cancel the race.
change of plan!
use the
information on
the map
With reference to the
synoptic chart, explain why
this advice was given.
5 marks
number of points to
make
LINK QUESTION TO THE MAP
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
Tightly packed
isobars : strong
winds
South
westerly
winds
Associated
weather is
moving west
to east
Centre of low
pressure : likely
to bring stormy
weather
Warm mT air
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 –
mP air mass
• Heavy rain – occluded front
• Low cloud and poor visibility – occluded front
5 marks
2014
EXAM QUESTION
QUESTION
Give reasons for the differences in
the weather conditions between
Ballycastle and Lerwick?
(5 marks)
MARKING SCHEME ANSWER
•
It is much windier at Ballycastle than Lerwick because the
isobars are much closer together in Ireland (1);
•
it is raining heavily at Ballycastle because it is next to the
cold front whereas Lerwick is not close to any fronts (1);
•
the wind direction is north west at Ballycastle and south
east at Lerwick because the wind goes anticlockwise
around the low pressure and the isobars show the
approximate direction (1);
•
the cloud cover is 8 oktas at Ballycastle because it is so
close to the cold front where there is likely to be
cumulonimbus cloud whereas Lerwick is not near any
fronts so is less likely to have cloud (1);
•
the temperature is warmer at Ballycastle as it is still in the
warm sector whereas Lerwick is not (1); the weather is
mostly worse in Ballycastle than Lerwick as it is closer to a
depression (1).
•
It is warmer in Ballycastle because the clouds trap the
heat whereas it is colder in Lerwick because there are no
clouds (1)