Pressure and Rainfall

Investigating the Link Between Between Pressure and Rainfall

Teachers Notes

Here is some data collected by a weather station on the outskirts of Edinburgh, at the start of 2019.

Date

Atmospheric Pressure (hPa)

Rainfall (mm)

10/12/2018

1025

0.0

11/12/2018

1020

0.0

12/12/2018

1019

0.0

13/12/2018

1022

0.0

14/12/2018

1017

0.0

15/12/2018

988

1.0

16/12/2018

1005

5.1

17/12/2018

1005

0.3

18/12/2018

996

1.5

19/12/2018

995

0.3

20/12/2018

995

0.5

21/12/2018

1000

0.5

22/12/2018

1014

0.0

23/12/2018

1027

0.0

24/12/2018

1032

0.3

25/12/2018

1026

0.3

26/12/2018

1023

0.0

27/12/2018

1023

0.0

28/12/2018

1022

0.0

29/12/2018

1030

2.3

30/12/2018

1030

0.3

31/12/2018

1026

0.0

01/01/2019

1044

0.0

02/01/2019

1043

0.0

03/01/2019

1041

0.0

04/01/2019

1039

0.0

05/01/2019

1034

0.0

06/01/2019

1031

1.0

07/01/2019

1024

0.0

08/01/2019

1033

0.0

09/01/2019

1031

0.0

Using this data, draw a graph of rainfall against pressure.

graph paper

Now use this information to complete the following sentences:

The most it rained in one day was _______________mm.

It didn’t rain at all on ____________ days.

The highest pressure recorded was ______________hPa (a hPa is the same as a millibar).

The lowest pressure recorded was _______________hPa.

Does it always rain when the pressure is low? Use figures to justify your answer.

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Does it ever rain when the pressure is high? Use figures to justify your answer.

____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Many weather apps assume that if the pressure is low, it will rain. Does your graph justify this assumption?

_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

 

 

Extension:

Here are the weather maps for 4 of the days when it rained: the first 3 show when the pressure was low and the 4th shows when the pressure was high and it rained.

1)

2)

3)

4)

Passage of a Depression – Animation

Depressions, Anticyclones and Fronts

Passage of a Depression – interactive animation

Worksheet to accompany the animation.

For 11+

Depressions from our Weather and Climate teacher’s guide

Pop-up depression

Cold and Warm fronts activities for differentiation and revision

Finding weather features on a simple synoptic chart

Red sky at Night, Shepherd’s Delight worksheet and Teacher’s Notes – a resource looking at how our prevailing wind direction means this saying is largely true.

Depressions Taboo

For 14+

Weather systems PowerPoints and cross section practice

Using WOW data to investigate a depression passing across the UK with  worksheets for students including isoline drawing practice.

Anticyclones, depressions and fronts with student worksheets 

Depressions and anticyclones with a synoptic chart exercise

A case study of orographic rainfall in Scotland.

What is the weather? Work out what the weather is like at several UK locations based on some simplified weather maps.

Interpreting weather charts basic information on synoptic charts, with Isotherm map exercise and Synoptic chart exercise.

Isotherm and Isobar drawing exercise based on a depression on our contour resources page.

For 16+

UK Synoptic Charts: Pressure and Wind Skills Exercise

Skills Exercise



You will need an Atlas for these activities

  1. Identify on the map a country experiencing HIGH pressure.                                                
  2. What type of air pressure is arriving in the UK?                                                                                            
  3. What is the lowest value of pressure shown on the map?                                                                           
  4. What is the air pressure over Greenland?                                                                                                     
  5. What is the air pressure over Northern Africa?                                                                                
  6. Identify an area that would have STRONG winds (the isobars will be close together)                                                                                                                    
  7. Identify an area that would have WEAK winds (the isobars will be far apart)                                 

 

EXTENSION– can you draw simple arrows to show the pattern of wind over the UK on the small inset map? (recall that wind moves from high to low and is deflected to the left in the Northern hemisphere) 

 

17. Depressions

Weather and Climate: a Teachers’ Guide

Pathway: Extending Weather

 Pressure and WindWater in the AtmosphereAnticyclones – Depressions

Lesson overview: In this lesson we look at the causes of Low pressure systems and the weather they bring to the UK.

Depressions or low pressure weather systems, bring most of the ‘normal’ and ‘extreme’ weather that we experience in the UK.  Driven by rising air, they mix colder and warmer air masses, forming fronts where these meet and bringing a predictable progression of weather as they pass over the UK.  Their approach is typically first signalled by high cirrus cloud, which eventually develops into rain-bearing stratus.  Once this passes there may be higher temperatures and less precipitation for a while, before towering cumulonimbus clouds arrive bringing heavy rainfall followed by lower temperatures and scattered showers.

Learning objectives:

  • To understand what low pressure is.

  • To know what weather a depression system brings to the UK.

  • To be able to draw and explain weather fronts.

  • To understand how weather changes in the UK as a depression passes over

Key Teaching Resources

Depressions PowerPoint
Depressions PowerPoint (easier)
Depressions Worksheet
Depressions Worksheet (easier)
Depressions Homework
Depressions animation worksheet
Pop-up Depression

Teacher CPD/ Extended Reading

Depressions_More for Teachers

Alternative or Extension Resources

Further resources for teaching about depressions, anticyclones and fronts.

Alternatively … you could get today’s weather chart and ask students to write a forecast for a place in the UK … or capture the weather forecast, from YouTube or similar, without the sound and ask students to write (and present) the commentary to go with it.

Weather and Climate: a Teachers’ Guide

16. Anticyclones

Weather and Climate: a Teachers’ Guide

Pathway: Extending Weather

Air MassesPressure and WindWater in the AtmosphereAnticyclones

Lesson overview: In this lesson we look at the weather associated with anticyclones in summer and winter and its potential impacts.

Anticyclones are high-pressure weather systems caused by descending air.  They rotate clockwise as outflowing air at ground level is deflected by the Coriolis effect and bring light winds and warm sunny days in the summer, but also crisp winter days and endless gloom in spring.  Large high-pressure systems can sit in place for long periods of time and deflect low-pressure weather around the UK.  This can lead to protracted periods of stable weather with little precipitation.

Learning objectives:

  • To understand what an anticyclone is.

  • To be able to distinguish between the weather in a winter and summer anticyclone.

  • To be able to explain why we get high pressure in an anticyclone.

  • To understand the positive and negative impacts of anticyclones in summer and winter

Key Teaching Resources

Anticyclones PowerPoint
Anticyclones PowerPoint (easier)
Anticyclones Worksheet
Anticyclones Worksheet (easier)
Anticyclones Homework

Teacher CPD/ Extended Reading

Anticyclones_More for Teachers

Alternative or Extension Resources

Further resources for teaching about anticyclones, depressions and fronts. 

Weather and Climate: a Teachers’ Guide

Depressions – Identifying Features

Identify the weather features on the synoptic (weather) chart below:

Cold Front

Warm Front

Highest pressure

Depression

Anticyclone

Isobar

Occluded Front

Strong Wind

Light Wind

Lowest Pressure

 

Advanced

Northerly Wind

Northwesterly Wind

Southwesterly Wind

 

(hint the clouds in the images below are cirrus, cumulonimbus, cumulus and nimbostratus)

cirrus
cumulus
Cumulonimbus
synoptic chart extract

Pop-up Depression

Print, cut-out and fold along the lines to make a 3D model of a depression. 

Depression
Depression with folding instructions

Passage of a Depression – Account

Passage of a depression

Use the following help sheet to write a fictional story about the passing of a depression. Imagine you are in the field taking observations and measurements. You should use all the statements included below.

 Coming of the warm front At the warm front Within the warm sector At the cold front Within the cold sector
 Barometer – shows pressure is falling Barometer – continues to show the pressure is falling. No significant changes on the barometer. Suddenly the pressure on the barometer begins to rise. Pressure continues to rise.
 Thermometer – shows the temperature is steady Thermometer – shows the temperature is rising. Feeling a little sticky in this heavy coat! Still quite mild. Time for a hat, and to button up that coat, the temperature is falling, it’s becoming chilly. It remains cold.
 Cirrus clouds high in the sky, they begin to descend and thicken becoming altostratus. Becomes darker, the clouds are low and cover the sky like blankets – nimbostratus. Starting to see breaks in the cloud, a little drizzle now – nothing heavy. Angry looking clouds, towering and grey, begin to form – cumulonimbus. The clouds have thinned out now – some cumulus.
 No need for the umbrella yet! Time to get out the umbrella, continuous heavy rain. A steady breeze, nothing too uncomfortable. Heavy rain! Is that thunder I hear? A few showers.
 Slight increase in wind speed. The wind is much stronger now – struggling to hold onto my umbrella.  Struggling to stay on my feet, as I’m battered by the strong winds. Time to go home I think!

What is the Weather

For each location marked on each map, what do you expect the weather to be doing? Think about whether it is windy, what the wind direction is, whether it is raining and whether it is warmer or colder.

 

weather map

Galway __________________________________________________________________

Aberdeen __________________________________________________________________

London __________________________________________________________________

weather map

Glasgow __________________________________________________________________

Norwich __________________________________________________________________

Exeter __________________________________________________________________

weather map

Tiree __________________________________________________________________

Carlisle __________________________________________________________________

Norwich __________________________________________________________________

weather map

Tiree __________________________________________________________________

Leeds __________________________________________________________________

Brighton __________________________________________________________________