All About Ra in

• To explain how rain can be formed.• To use an atlas to locate an area.• To describe geographical patterns in rainfall.

• To understand how the three types of rainfall are formed.Learning Object ive

Success Criteria

How many weather key terms can you make from these letters in one minute (you can use each letter more than once).

Slide Tit le

Did you find any of these?clouds, anemometer, thermometer, precipita tion, cirrus, cumulus, cloud droplet, condensation, condensation nuclei, barometer, a ir pressure, tornado, storm

C D O R M S A

B E L T P I U

H

N

Can you remember how clouds and rain form?

How Do Clouds and Rain Form?

Warm air containing water vapour rises.

As the warm air rises, it cools.

Water vapour condenses into tiny dust particlesin the air, forming a cloud droplet.

Billions of cloud droplets together form a cloud.

Cloud droplets join up to make larger, heavier droplets, which fall as ra in!

Types of Ra infa ll

Take NotesComplete your Types of Ra infa ll Activity Sheetas you learn about thedifferent types of ra infall.

1. convectiona l ra infa ll – rain formed when the ground heats up during warm, sunny weather.

Types of Ra infa ll

1. The sun heats the ground causing any moisture to evaporate and form water vapour.

2. As the warm, moist a ir rises it cools and condenses into clouds and eventually rain.

1. convectiona l ra infa ll – rain formed when the ground heats up during warm, sunny weather.

Types of Ra infa ll

This type of ra infall is most common in the south and east of the UK.

Can you suggest a reason why?

These a reas a re usua lly warmer and have more sunshine!

Convectiona l ra infa ll is very common in the tropica l ra inforests –can you suggest why?

2. relief ra infa ll – rain formed when air is forced to rise over a hill or mountain. (Relief means the shape of the land.)

Types of Ra infa ll

1. The prevailing wind brings, warm, moist a ir from the ocean.

2. The air is forced to rise over hills or mountains.

3. The rising air cools and the water vapour condenses to form clouds and rain.

4. As the air descends on the other side of the mountain, it warms up and becomes drier.

Relief map of the UK

Relief ra infall is most common along the west coast of the UK. Can you suggest a reason why?

Types of Ra infa ll

There a re hills and mounta ins a long the west coast of the UK which force moist a ir from the Atlantic Ocean to rise.

3. fronta l ra infa ll – to understand how frontal ra infall forms, you need to know a bit about a ir masses!

Types of Ra infa ll

What is an a ir mass?

An air mass is a large mass of a ir which moves over the Earth’s surface.

The temperature of an air mass depends on where it has come from.

For example, a polar a ir mass comes from the polar regions, so will bring cold air.

We will look at a ir masses in more detail in the next few lessons!

Pola r Marit ime

ArcticPola r Continenta l

Tropica l Continenta lTropica l Marit ime

3. fronta l ra infa ll – occurs when two air masses meet.

Types of Ra infa ll

1. When a warm air mass meets a cold air mass, they do not mix; they have different densities.

2. The warm, less dense air is forced to rise over the cold, dense air. This is called a front .

3. The warm air cools and the water vapour condenses into clouds and rain.

warm air(less dense)

cold air(denser)

front

Frontal rainfall can happen anywhere in the UK. Can you suggest a reason why?

Types of Ra infa ll

This type of ra infall can happen anywhere in the UK, because the air masses can meet anywhere.

However, a ir masses frequently meet over the Atlantic Ocean, so frontal ra infall is very common on the west coast.

Complete your Rainfa ll Activity Sheet .

Types of Ra infa ll

What do these types of rainfall have in common?

What a re the differences between them?

Same But Different!

convectional ra infall relief ra infall

frontal ra infall