KS3 · Geography

Why does the UK have such variable weather?

Sunny at breakfast, rain by lunch, a gale by teatime. UK weather loves changing its mind, and the answer hides in two-word names like 'tropical continental'.

Geography · UK weather

Decode the air mass name

An air mass name pairs a temperature word (tropical, polar, arctic) with a wetness word (maritime, continental). Tropical means warm; polar and arctic mean cold; maritime means wet; continental means dry. Tick every set each air mass belongs in: Warm, Wet, both, or neither.

  • A Warm
  • B Wet
  1. Tropical maritime
  2. Tropical continental
  3. Polar maritime
  4. Arctic maritime
  5. Polar continental

Exam line: Name = temperature + wetness. Tropical is warm; arctic and polar are cold. Continental is dry; maritime is wet.

Depression vs anticyclone

DepressionvsAnticyclone

Forecasts can be shown on synoptic charts. Air pressure is drawn as isobars, and weather fronts (cold and warm) are marked. Symbols show the weather to expect, such as a sun for a sunny day and a cloud for a cloudy day.

Focus

Pressure

Depression

Low pressure

Anticyclone

High pressure

The insight

Pressure is a force pressing on a given area. Whether it is low or high depends on what the air is doing.

Air movement

Depression

Air is rising

Anticyclone

Air is sinking

Isobars on a synoptic chart

Depression

Closely spaced

Anticyclone

Widely spaced

Wind

Depression

Windy: higher wind speeds

Anticyclone

Very gentle winds

Weather

Depression

Rain, wind and cloud

Anticyclone

Dry, stable weather

What else it can bring

Depression

Changeable temperatures and rain where warm and cold air meet (at a front)

Anticyclone

Summer heatwaves, or very cold conditions in winter

Geography · Rainfall

What makes the air rise?

Rain forms when air rises, cools and condenses. So what decides the type of rainfall? What makes the air rise. Sort each description into relief, convectional or frontal rainfall.

Still to sort

Relief rainfall (0)

Air is forced up by the land itself

Where the line is: Relief and frontal both involve air being forced upwards. In relief rainfall it is the height and steepness of the land that does it, not another air mass.

Convectional rainfall (0)

The sun heats the land

Where the line is: Here the air rises because the sun has heated the land, not because of mountains or another air mass.

Frontal rainfall (0)

A warm air mass meets a cold air mass

Where the line is: Here it is two air masses that do the forcing. They do not mix easily, so the warm air is pushed up over the cold air.

6 of 6 still to sort.

Exam line: All three types finish the same way: the air rises, cools and condenses. The type depends on what makes it rise.
Watch out: Frontal rainfall is a warm AIR MASS meeting a cold AIR MASS, with the warm air forced to rise over the cold. It is not 'a warm front meeting a cold front'.

Latitude

?

Reason it through

The UK has a temperate maritime climate: mild, with rainfall all year. So why is the north colder than the south?

Link 1 of 3

First link · your turn

Think about the sun's rays at higher latitudes, the further north you go. What happens to them?

2
Locked — reveal the link above first
3
Locked — reveal the link above first

Geography · UK regions

The UK's four climate regions

First, the seasons. The Earth is tilted on its axis, so in summer the northern hemisphere (where the UK is) points towards the sun, giving warmer temperatures and longer days. In winter it points away, giving colder temperatures and shorter days. Now the regions. For each one, tick what you think is true, then check.

North West
South West
North East
South East

Exam line: Climate varies from region to region. Read down the columns for the patterns: west and east, north and south.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Air masses, pressure and rain, and why the north and south feel different

What you need to know

  • Weather is the day-to-day condition of the atmosphere; climate is its average over a long time, usually 30 years or more.
  • Have a goDev looks out at a sunny Monday and announces, 'The UK's climate is sunny!' Has Dev described weather or climate?

    Weather.

    One sunny day is a day-to-day condition. Climate is an average over a long time, usually 30 years or more.

  • The UK has a temperate maritime climate: mild, with rainfall all year round.
  • The UK's climate varies by region. The further north, the colder: at higher latitudes the sun's rays spread over a larger area.
  • Where the land is higher, there tends to be more precipitation, mainly in the west of the UK.
  • An air mass is a large pocket of air with the same temperature and humidity, set by where it comes from.
  • An air mass name has two clues: tropical is warm, arctic and polar are cold; continental is dry, maritime is wet.
  • Have a goA forecaster mentions a tropical continental air mass. Before you look back: is it warm or cold, and dry or wet?

    Warm and dry.

    Tropical is warm and continental is dry. The name is just a temperature word plus a wetness word.

  • Air masses meet over the UK but don't mix easily, so they compete. That's why UK weather is so changeable.
  • Low pressure (rising air) is a depression: rain, wind, cloud. High pressure (sinking air) is an anticyclone: dry, stable weather.
  • Have a goAir is sinking over a town. Is that high or low pressure, and what is that kind of system called?

    High pressure: an anticyclone.

    Sinking air means high pressure. Rising air is low pressure, which is a depression.

  • On a synoptic chart, isobars join equal pressure. Close together means stronger winds; further apart means gentler winds.
  • Rain falls three ways (relief, convectional and frontal), and they differ in what makes the air rise.

The big picture

The UK's weather changes so often because air masses with different temperatures and wetness meet and compete over it. Its climate differs from region to region because of latitude and altitude. Pressure systems (depressions and anticyclones) bring different weather, and three kinds of rainfall depend on what makes the air rise.

Key points

1Weather is the day-to-day condition of the atmosphere (sunny, snowing, warm). Climate is the average of weather conditions, such as rain, sun and wind, over a long period, usually 30 years or more.
2The UK has a temperate maritime climate: moderate rainfall, mild to warm summers, cool to cold winters, and precipitation all year round.
3The UK has seasons because the Earth is tilted on its axis. In summer the northern hemisphere points towards the sun (warmer, longer days); in winter it points away (colder, shorter days).
4The UK's climate is not the same across the country. It varies by region because of latitude, altitude and air masses. The south is warmer than the north, and the west is wetter than the east.
5Latitude: the further north, the colder, because at higher latitudes the sun's rays are spread over a larger area and the solar energy is less concentrated on the land. Altitude: where the land is higher there tends to be more precipitation, mainly in the west.
6Air masses are named by pairing a temperature (tropical warm; arctic and polar cold) with wetness (continental dry; maritime wet). A tropical continental air mass brings hot, dry weather; an arctic maritime air mass brings cold, wet or snowy weather.
7Air masses all meet over the UK and do not mix easily, so they compete. That makes the weather so changeable, and when air masses collide it can sometimes be extreme.
8A depression is low pressure with rising air, rain, wind and cloud, and closely spaced isobars. An anticyclone is high pressure with sinking air, dry, stable weather, very gentle winds and widely spaced isobars. Anticyclones can bring summer heatwaves and very cold conditions in winter.
9Relief rainfall: warm moist ocean air rises over mountains. Convectional: the sun heats the land and warm air rises. Frontal: a warm air mass meets a cold air mass and the warm air is forced up over it. In each, the rising air cools and condenses.
10Synoptic charts display weather forecasts: isobars show air pressure, cold and warm fronts are marked, and symbols show the weather to expect, such as a sun or a cloud.

Worked example

Problem

You are reading two forecasts. Monday's names a tropical continental air mass arriving over the UK. Wednesday's synoptic chart shows isobars squeezed close together over the country. What weather should you expect on each day?

⚠ Watch out

Tempting idea: the UK has one climate everywhere and random weather. Not so. Climate varies by region (latitude, altitude, air masses), and weather changes because air masses meet and compete. Also: frontal rain is a warm air mass meeting a cold one, not 'a warm front meets a cold front'.

🧠

Memory hook

Tropical = toasty. Polar and Arctic = chilly. Maritime starts with M, like Moist, so continental is the dry one. Name = temperature + wetness.

✓

Check yourself

Try a name we haven't met: arctic continental. What two things does it tell you, and which Venn circle(s) would it sit in? Then say why the UK's weather keeps changing.

Flashcards

(16)
How are weather and climate different?
Weather is the day-to-day condition of the atmosphere (sunny, snowing, warm). Climate is the average of weather conditions over a long period, usually 30 years or more.
What does 'temperate maritime' tell you about the UK's climate?
It is mild, with rainfall all year round: moderate rainfall, mild to warm summers, cool to cold winters.
Why does the UK have seasons?
The Earth is tilted on its axis. In summer the northern hemisphere points towards the sun (warmer, longer days). In winter it points away (colder, shorter days).
Why is the north of the UK colder than the south?
At higher latitudes the sun's rays are spread out over a larger area, so the solar energy is less concentrated on the land.
How does altitude affect the UK's climate?
Where the land is higher there tends to be more precipitation, mainly in the west of the UK.
What is an air mass?
A large pocket of air with the same temperature and humidity, whose characteristics are set by where it comes from.
Maritime or continental: which is wet, which is dry?
Maritime is wet. Continental is dry. (Tropical is warm; arctic and polar are cold.)
Why is the UK's weather so changeable?
Air masses all meet over the UK and do not mix easily, so they compete. When they collide the weather can sometimes be extreme.
What is pressure, and what do low and high pressure mean?
Pressure is a force pushing on a given area. Low pressure is where air is rising. High pressure is where air is sinking.
What is a depression?
An area of low pressure where air is rising, with rain, wind and cloud. Warm and cold air meet there, giving changeable temperatures and rain.
What is an anticyclone?
A high pressure system where air is sinking: dry, stable weather with very gentle winds. It can bring a heatwave (a prolonged period of abnormally hot weather) in summer and very cold conditions in winter.
What is a front?
The boundary between a warm air mass and a cold air mass. Synoptic charts show cold and warm fronts.
What are isobars, and what does their spacing tell you?
Lines on a synoptic chart joining places of equal air pressure. Close together: steep pressure gradient and higher wind speeds. Further apart: pressure changes gradually and winds are gentler.
What is relief rainfall?
Warm moist air from the ocean rises up over mountains, cools and condenses, forming rain. Relief is the physical shape of the land, including its height and steepness.
What is convectional rainfall?
The sun heats up the land, warm air rises, and as it cools and condenses it forms rainclouds.
What is frontal rainfall?
A warm air mass meets a cold air mass. They do not mix easily, so the warm air is forced up over the cold, cools, and its water vapour condenses into clouds that fall as rain.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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