Age Range: 16 to 18

Particulate Matter, ice, albedo and melting – Teacher’s Notes

Post date 15 March 2021

In this experiment the students will look at the effect of Particulate matter or other substances that have landed on ice and test how this can speed up the melting of ice by affecting its albedo. Particulate Matter and aerosols are made up of a variety of pollutants, some of them enhancing and some counteracting the greenhouse effect when they are in the atmosphere. But once they land on snow or ice, they will promote the melting of these surfaces.

Chemistry Curriculum Links AQA GCSE

9.2.3. Properties and effects of atmospheric pollutants

Particulate Matter is a pollutant that absorbs at many different wavelengths, some act as greenhouse gases and others actually reflect more light than they absorb, leading to a reduction in the temperature of the atmosphere. When they (or Black Carbon in particular) deposit on snow and glaciers, they change the albedo (the reflectivity) of the snow surface. This controls the heat balance at the surface of snow and ice surfaces as the darker colour of the ice will lead to it melting faster.

Particulate Matter is solid particles that are so small that they float in the atmosphere and can be measured as a concentration in the atmosphere. They are formed from incomplete combustion of wood and fossil fuels. PM smaller than 2.5 microns (2.5 x 10^-9 m), PM_2.5 , is much smaller than the width of a human hair and can enter into our lungs and be carried into the blood system and cause damage to the brain and the cardiovascular system.

Uncertainties to do with the quantities of the different particles in the atmosphere (and the fact that particles enhance cloud formation) are part of the biggest current uncertainty in climate models.

Class Practical

This experiment can be carried out in pairs or larger groups and takes about 20 minutes.

Follow the notes in the student worksheet, allowing more time to discuss what particulate matter is, what is albedo and how sunlight is absorbed differently by different coloured substances.

Discussion Questions

Which ice cubes melted faster? Was it what they expected?
Did all groups get similar results? Can we compare the melting rates as a % of original mass and see if they are similar between groups? What is the error in the melting rate of the 3 types of ice cubes?
Does covering them with brown or black melt them faster?
What are the possible errors in the experiment?

Application to the World’s Glaciers:

Glaciers around the world are more exposed to particulate matter now than they ever were before the industrial revolution and the increase in industry and cars over the last century. Covering snow and ice with a dark layer changes the albedo and they absorb more heat and melt quicker than the pure ice.

Particulates are tiny solid or liquid particles that are present in the atmosphere. They are sometimes termed aerosols when they float in the air. Examples are dust, spores and pollen, salt from sea spray, volcanic ash and smoke. Black carbon (elemental carbon (soot) or organic carbon) from incomplete combustion in the atmosphere can actually absorb incoming solar radiation and cool the Earth. However, when these particles land on ice, the absorption of radiation will enhance the ice´s melting.

References

Iain Stewart BBC black ice experiment

UN Environment programme, 2019: Glaciers are melting and air pollution is the cause

See bar chart of radiative forcing of various gases or particulates in Fig 14.4 Ramaswami et al., 2019

Ocean Acidification – Worksheet

Post date 15 March 2021

icebergs — Icebergs are on the arctic ocean in ilulissat icefjord. Nature and landscapes of Greenland.

Increased CO₂ levels in the atmosphere are buffered by the oceans, as they absorb roughly 30 % of this CO₂. The negative consequences of this are that the oceans become more acidic. The CO₂ reacts with water and carbonate to form carbonic acid, reducing the available carbonate that shellfish, crabs and corals combine with calcium to make hard shells and skeletons.

Materials

Chemicals	Apparatus
Bicarbonate of soda (1/2 teaspoon)	2 x 500 ml Beakers
White vinegar (1 teaspoon)	Small plastic or paper cup (100 ml)
Indicator: Bromothymol blue (Diluted with water: 8 ml bromothymol blue (0.04% aqueous) to 1 litre of water)	Masking tape
	2 x Petri dishes or lid for large beakers
	Safety glasses and lab coat
	Teaspoon or 5 ml measuring cylinder
	Two sheets of white paper

Method

Pour 50 ml of the indicator solution into both beakers.
Add 1/2 teaspoon (2 grams) of bicarbonate of soda to the plastic cup.
Tape one paper cup inside one beaker containing the indicator solution so that the top is about 1 cm below the top of the beaker. Make sure the bottom of the paper cup doesn´t touch the surface of the liquid in the plastic cup. The other beaker will be your control.
Place both clear plastic cups onto a sheet of white paper and arrange another piece of white paper behind the cups as a backdrop (so you can see any colour change).
Carefully add 1 teaspoon (5 ml) of white vinegar to the plastic cup containing the bicarbonate of soda. Be very careful not to spill any vinegar into the indicator solution. Immediately place a Petri dish over the top of each beaker.
Position yourself so you are at eye level with the surface of the indicator solution, ready to see a colour change occurring.

Results

What colour does the solution that contains the plastic cup change to?
Vinegar (acetic acid) and bicarbonate of soda (Sodium bicarbonate) react to produce CO2 that is now present in the atmosphere of the large beaker, in contact with the indicator solution (the ocean). Some of the CO2 starts to absorb into the ocean, changing its pH.
A colour change from blue to yellow represents a reduction in pH. Is the solution (the ocean) becoming more acidic or more basic?

Application to the World’s Oceans

Corals and shellfish can be affected by ocean acidification, making it harder to create their shells, which will affect other fish up through the food web.

Corals and fish can be affected by slight changes in the temperature of the water and the next experiment also shows the effect of temperature increase on CO₂ absorption, creating a positive feedback, a knock-on effect.

Ocean CO2 Absorption – Worksheet

Post date 15 March 2021

Does warm or cold water absorb CO₂ better?

If the oceans are absorbing large quantities of water, and if we know the oceans are warming due to global warming, what is the effect of warmer oceans on CO₂ absorption? Let´s check with this experiment that shows how much CO₂ will dissolve in the water and how much will be in its gaseous form above the water.

Materials

Chemicals	Apparatus
Water	2 x 500 ml measuring cylinders
Effervescent fizz tablets (e.g. Alka Seltzer)	2 x Petri dishes that fit over the cylinders
Ice (optional)	Bowl or container of at least 5 litres
	Stand and clamp to hold cylinders
	Water heater
	Funnel (optional)

Method

Fill the basin half-full with cold (or iced) water. Place the stand beside the basin.
Fill the graduated cylinder to the brim with cold water and cover the top of the cylinder with the petri dish. Turn it upside down in the basin, making sure that no water spills out of the cylinder (so no air bubble forms). Remove the Petri dish when the cylinder is already underwater.
Secure the graduated cylinder with the clamp to the stand and place the funnel in the mouth of the cylinder.
Place an effervescent tablet carefully under the funnel. (Be sure your hands are dry so as to not set off the reaction prematurely).
Observe the air space that develops at the top of the upside-down cylinder. Record the volume of the air space formed.
Repeat the same procedure with warm water and record your results in the table. What happens to the air space when warm water is used? Is more or less air released than with cold water?
Repeat the same experiment two or three times more with both cold and warm water.

Results table

Experiment number	WARM water (volume of air/ml)	Experiment number	COLD water (volume of air/ml)
1		1
2		2
3		3
4		4
AVERAGE volume		AVERAGE volume

Question: Does more CO₂ escape from warm or cold water?

If more has escaped from the liquid, the water cannot absorb as much CO₂.

Extension Question: With global warming and warmer oceans, will the oceans be able to absorb more or less CO₂ than before?

What is the perfect pH of the oceans? Is it different depending on which ocean and whether it is in the deep ocean or the shallower coastal areas?

Ocean Acidification and CO2 Absorption – Teacher’s Notes

Post date 15 March 2021

Curriculum Links: Core chemistry AQA GCSE

4.2.4 The pH scale

9.1.2 The Earth´s early atmosphere

9.2.3. Global climate change

Chemistry in the activity

Na₂CO₃ + 2 CH₃COOH → 2 CH₃COONa + CO₂ + H₂O (Bicarbonate of soda reacts with vinegar to form carbon dioxide)

In this experiment the students will initiate a reaction that produces CO₂ in an enclosed water-air environment. The CO₂formed will be absorbed into the water, making it more acidic and changing the colour of the indicator. The experiment can be carried out in pairs and takes about 15 minutes. An additional experiment to test the solubility of CO₂ in warm and cold water can be carried out afterwards, explaining how global warming can affect marine CO₂ absorption.

Materials

Bicarbonate of soda (baking soda)
White vinegar
Bromothymol blue Indicator (diluted with water: 8 ml bromothymol blue (0.04% aqueous) to 1 litre of water)
2 x 500 ml Beakers
Small plastic or paper cup (100 ml)
Masking tape
2 x Petri dishes or lid for large beakers
Teaspoon or 5 ml measuring cylinder
Two sheets of white paper
Safety glasses and lab coat

See the student worksheets for the detailed preparation: Ocean acidification and CO₂ Absorption

Application to the World’s Oceans

The beaker is like an enclosed ocean-atmosphere and the CO₂from the reaction will equilibrate between the water and the air. Our oceans absorb more CO₂ when the concentration in the atmosphere increases. But how much CO₂ can they keep absorbing? Will they reach a saturation point?

Corals and shellfish are affected by ocean acidification, making it harder to create their shells, which will affect other fish up through the food web. Global warming caused by the increased CO₂effects the corals and fish as only slight changes in the temperature of the water can have effects throughout the ocean´s food chain. So there is a knock-on effect or a positive-feedback from the ocean heating and the ocean acidification.

If you want to illustrate more about the feedbacks and this double impact, the next experiment demonstrates the effect of a temperature increase on CO₂ absorption, thus limiting the water´s capacity to absorb as much CO₂.

CO₂ Absorption in Water class practical

This experiment allows students to determine how much CO₂ dissolves in warm or cold water.

See the student worksheet for the detailed preparation.

Materials

Water
Effervescent fizz tablets
Ice (optional)
2 x 500 ml measuring cylinders
2 x Petri dishes that fit over the cylinders
Bowl or container (at least 5 litres)
Stand and clamp to hold cylinders
Water heater
Funnel

Application to the World’s Oceans:

More CO₂ has escaped from the warm water, showing that it cannot absorb as much CO₂. Warmer oceans will not be as effective buffers at removing CO₂ from the atmosphere. However, this phenomenon does prevent these warmer oceans from being as acidic.

References

National Oceanic and Atmospheric Administration (NOAA) Ocean acidification Educational resources
Exploratorium Science snacks, Ocean Acidification in a Cup
CarboEurope cold and hot water CO₂ absorption experiment
For a follow-up class: CarboEurope: Uptake of Carbon Dioxide from Water by Plants

Particulate Matter, ice, albedo and melting – Worksheet

Post date 15 March 2021

Have a look at these two glaciers, one has fresh snow over the glacier and the other is a dry glacier in summer with accumulated deposits of dust and Black Carbon from air pollution. Which one do you think is more vulnerable to melting? Does a bright white surface reflect more or less light than a darkened surface?

Fresh clean snow on the Silvretta glacier, Switzerland (Zoë Fleming)

Dirty ice on the Fox Glacier, New Zealand (Sylvia Knight)

Particulate Matter is solid particles that are so small that they float in the atmosphere. They are formed from incomplete combustion of wood and fossil fuels. When they are smaller than 2.5 microns (2.5 x 10^-9 m, an eight the width of a human hair), this PM_2.5 can enter into our lungs and be carried into the blood system and cause damage to the brain and the cardiovascular system.

When Particulate Matter (or Black Carbon, which is more or less soot or pure Carbon) settles on glaciers and snow it darkens the colour of the snow and hence changes the how much of the Sun’s light the snow reflects. In this experiment we will check to see whether dirty or clean ice melts faster.

Materials

Chemicals	Apparatus
3 ice cubes per group	3 bowls for placing ice cubes
Soot or Activated Carbon or burn a splint and gather the blackened combusted material	Spotlight
Soil or sand (as light coloured as possible)	Measuring scale
	Spoon or forceps to move the ice cube between the bowl and the measuring scale

Method

Take 3 ice cubes out of the freezer and place one in each bowl.
Scatter soot over the ice cube in one bowl, covering it completely. Scatter the next ice cube with the soil. The last bowl will contain the control ice cube.
Weigh each ice cube (using a spoon or forceps to place it on the scale).
Shine the light bulb over the 3 bowls, trying to equally light/heat them all.
After 5 minutes, remove each ice cube one at a time to weigh them.
After 10 minutes, remove each ice cube one at a time to weigh them.
If you have time to wait for the first ice cube to completely melt, note the time and note down how much was left of the other ice cubes (weigh them).

Results and Questions

Which ice cubes melted faster?
Does covering them with brown or black melt them faster?
Thinking about a sunny day on snow, how do your eyes react to the sunlight? Does it seem like there is more light around or less than on a sunny day walking on bare soil? What about a sunny day on a boat? Do you think there is more or less light reflected back to your eyes than on land? The proportion of the Sun’s light which is reflected by a surface is called its albedo – a high albedo means a large proportion of the light is reflected and, therefore, only a small proportion is absorbed.
What about the difference between wearing white or black clothes on a sunny day- which one absorbs the sun rays and makes you feel warmer? Is that a small or large albedo?

Application for the world’s glaciers:

Glaciers around the world are more exposed to particulate matter now than they ever were before the industrial revolution. Covering them with a dark material changes the albedo. The darker the surface, the more of the Sun’s light is absorbed by the glacier, warming it and melting it.

Particulates are tiny solid or liquid particles that are present in the atmosphere. They are sometimes termed aerosols as they float in the air. Black carbon (soot) is a particulate released from incomplete combustion. It absorbs the Sun’s light, which actually helps to cool the Earth. However, when it lands on ice, the absorption of radiation speeds up the ice´s melting as the light is absorbed by the dark colour and heats up the ice.

Social and political perspectives:

Knowing that air pollution that reaches glaciers is increasing their melting faster than what would happen from air temperature changes alone, what do you think we can do in terms of laws or behaviour change?

How can we reduce soot and Black Carbon reaching glaciers? Emission control of cars? Banning domestic wood-burning? Have you heard of smokeless coal that can be used in stoves in smoke-free zones? And pellet stoves, are there fewer emissions from these?

Note: You could carry out your own experiment if you are lucky enough to get snow. Prepare two neat snow blocks or two snow-balls of similar size and cover one with gravel or sand and leave the other clean. Watch which one melts first.

Orographic (relief) rainfall and the Foehn Effect

Post date 10 March 2021

This case study or ‘mystery’ is taken from the afternoon of the 2^nd September 2013. It focusses on Scotland and N. England. It can be used for two different purposes – either to identify orographic/ relief rain (use images 2-6 below), or to go on to identify a case study of the Foehn Effect (use all images).

We recommend that teachers present students in groups with a series of images, sequentially, to allow them to work out what the weather is doing and why.

Expected Knowledge

Students should be

Familiar with a map of the UK
Know which way winds blow around a pressure system, and be able to identify fronts and pressure systems on a synoptic weather map
Know about the 3 main ways in which rain can form (frontal, convective or relief/ orographic rain)

Suggested Lesson Opener

Make a cloud in a bottle or watch the video.

Notes for Teachers

Students can be helped, where appropriate to identify some of these points

Image 1

Image 1 – temperatures in degrees Centigrade at 15Z (1500GMT) (copyright Met Office)

The temperatures show that it is considerably warmer on the East side of Scotland than on the West. Temperatures are up to 9°C warmer on the East.

Why?

Image 2

Image 2 – a synoptic chart at 12Z (1200GMT) (copyright Met Office)

There are no weather fronts over the UK, although the whole country is in the warm sector of a low pressure system over Iceland.
There is a High Pressure system to the SW of the UK
Winds blow clockwise around a High pressure system, and along the isobars
The wind is therefore coming from the west (westerly winds) over Scotland
Alternatively, you could consider the winds blowing anticlockwise around the Low pressure system to the North – this also indicates that the wind direction over Scotland is from the west.
[We would normally associate this with Polar maritime/ returning Polar maritime air, but, in this case, if you follow the isoline back, the air has come from further south, so is Tropical maritime in nature.]
We would generally expect clear skies over most of the UK in this situation.

Image 3

Image 3 – wind speed in knots at 15Z (1500GMT) (copyright Met Office)

Image 4

Image 4 – satellite image at 15Z (1500GMT) : (c) EUMETSAT / Met Office

This is a satellite image from 1500Z (1500GMT) showing visible radiation ie light. The white areas are where the Sun’s light is being reflected from clouds.

There is cloud over the west coast of Scotland and N. England

You can also see the cloud associated with the warm front to the East of the UK, and the cold front to the west.

There is no front over Scotland, so the rain is not frontal rain.

Image 5

Image 5: Rainfall on 2^nd September 2013 (copyright Met Office)

It is raining over the west coast of Scotland. Why?

There is no front there, so it is not frontal rain
Is it orographic rain or convective rain?

Image 6

A relief map of Scotland clearly shows the high ground on the East coast.

Synopsis

As the easterly winds blow in from the west, the air is forced to rise. As it rises, it cools until the rate of condensation is faster than the rate of evaporation. Cloud droplets form, which eventually become large enough to fall as rain.

Therefore, this rain is orographic or relief rain.

As the air descends again downwind of the mountains, the air warms and the cloud droplets evaporate.

As the cloud droplets form, they emit latent energy (heat) into the air around. This heat is remains in the air if the rain reaches the ground. This means that, downwind of the mountains when the air sinks, warms, and any remaining cloud droplets evaporate, there is more heat in the air than there was upwind of the mountains.

This is why temperatures were so much warmer on the east coast than on the west on this day!

Image 1

Image 2

Image 3

Image 4

Image 5

Image 6

Global Atmospheric Circulation and Precipitation

Post date 10 March 2021

Visit https://svs.gsfc.nasa.gov/4285 and play the animation showing most currently available global precipitation data.
Look at the map below. Circle any patterns of rainfall that you see.

3. What is the type of land is below these rainfall patterns? (Green is forest, brown is desert).

4. In what latitude bands are these rainfall patterns?

Use these terms to fill in the blanks below for Questions 5-8: Hadley, cloud, humid, Sun, cloud, rainfall, low, ground, Ferrel, fronts, Equator, Hadley, poles, rainfall.

5. Rainfall occurs when ______ air cools down. Air cools when it rises, or when it moves away from the _______.

6. The Atmospheric Circulation is driven by the _____. In the Tropics, the Sun warms the _____ which in turn warms the air above. hot air rises, leading to _____ and _______. This drives the ________ cells.

7. Colder air sinks at the poleward edge of the _______ cells and over the __________. Sinking air has no _______ or __________.

8. In the _______ Cells, rainfall is mainly associated with ____ pressure systems (depressions). Rainfall is mainly on the ________.

9. Complete the following table (Look at the map for help):

	Tropics	Sub Tropics	Poles
Skies	Clear/ Cloudy	Clear/ Cloudy	Clear/ Cloudy
Rain (or snow)-fall	Dry/ Wet	Dry/ Wet	Dry/ Wet
Pressure	High/ Low	High/ Low	High/ Low

10. Sketch what you think the Hadley Cell looks like in December and June by the images of the Earth below. Hint: the Equator and Tropics of Cancer and Capricorn are shown on the map.

Visit https://earth.nullschool.net/#current/wind/surface/level/overlay=precip_3hr/orthographic to see today’s rainfall patterns. Click on ‘Earth’ and then choose in the Overlay settings ‘3HPA’ to see the rainfall patterns together with surface wind speeds. Change in the settings the ‘Control’ to change the date and see rainfall patterns over time. Compare January and July rainfall patterns.

11. In the Tropics, how does the latitude of highest rainfall change between January and July? ___________________________________

12. How does this relate to the sketches you drew above? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Extension question: Why do you think you are asked to look at rainfall in January and July, rather than December and June? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Pressure and Rainfall

Post date 8 March 2021

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.

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 4^th shows when the pressure was high and it rained.

Air Masses: Case Studies

Post date 8 March 2021

Notes for Teachers

Pick one of the synoptic charts below. Can you work out where the wind over the UK is coming from? Try to ignore any fronts, and don’t think about how things might have changed in the past or be about to change in the future.

Now answer the following questions:

What is the wind direction over the UK?_______________

What is the air mass affecting the UK?_________________

Describe the weather, in terms of wind speed, direction, temperature, cloud and precipitation.

Would you expect any difference in the weather between day and night? __________________________________________________________________________________________________

Would you expect any difference in the weather between the sea/ the windward coast and inland regions? ____________________________________________________________________________________________________________________________________________________________

February 2015

February 2018

May 2020

October 2011

October 2017

November 2010

Passage of a Depression – Animation

Post date 1 March 2021

Worksheet to accompany the animation.

Chemistry Curriculum Links AQA GCSE

Class Practical

Discussion Questions

References

Materials

Method

Results

Application to the World’s Oceans

Does warm or cold water absorb CO₂ better?

Materials

Method

Results table

Curriculum Links: Core chemistry AQA GCSE

Chemistry in the activity