Material for school visits
This page contains material for presenting to primary
school children on the subject of weather forecasting and
thunderstorms. It was used on 12 March 2013 with Year 3 of
St Columba's College, St Albans (a boys' school), and took
around 3 hours with a short break. Feel free to reuse the
materials below. There are some tips and thoughts on what
worked well and what didn't.
Thanks to Chris Westbrook for his tornado slides, to
Carole Peubey, Roger Brugge, Rob Thompson and Emma Irvine
for their advice and ideas beforehand, and to Mr Bridge
and Mrs Brown for their help on the day and suggestions
for last-minute changes to the execution of the weather
Part 1: Weather forecasting
The purpose is to explain why weather forecasting is
useful and how weather forecasts are made.
Measuring the atmosphere
We start looking at how the atmosphere is measured from
the ground, using weather balloons and using
- Members of the Department of Meteorology can
borrow some hand-held anemometers from the laboratory
staff, and you can get the children to see what force on
the Beaufort scale they can blow. Set all the
instruments to mph first, if possible. Note that
depending on the age group they may ignore the decimal
point on digital instruments and report very high wind
- Likewise, you can borrow a broken RS92 radiosonde
plus an uninflated weather balloon and parachute, and
show them the instruments on it.
Weather forecasting game
This is a primary school version of
Forecast factory. The children sit in a 5x4 grid
(perhaps in pairs depending on the class size), each
representing a town in England and Wales. They then
make a 24-hour forecast in six timesteps. If this is
being done in Reading or St Albans then the interesting
question is whether they will get snow tomorrow (and so
school might be cancelled). Rather than getting them to
do the calculations for Euler's advection scheme (as in
the secondary school version), the children simply pass
sheets of paper representing the weather in the
direction of the wind to their classmates elsewhere on
the grid. Each weather sheet indicates the rain or snow
that falls in the 4-hour period - they write this down
and then at the end add up the 24-hour accumulations of
rain and snow for their town. Boundary values need to
be fed in at each timestep. Towards the end a tornado,
thunderstorm and blizzard enter the domain.
The materials needed are:
My tips are:
- Make sure the arrangement of the grid is very
clear to the children, e.g. by sticking tape down on
the classroom floor, or if you have small tables by
using each table as a town.
- Make sure that at the start all the weather sheets
are aligned north-up/south-down so that the children
interpret the arrows on the sheets correctly and pass
them in the right direction
- To help the children get an idea what's happening
in the whole domain, you can ask them at each timestep
"hands up who's got rain or snow" or "hands up who's
got a temperature of zero or lower" and point out the
fronts passing over and the big area of cold area
progressing across the country.
- At the end get them to read out their total rain
and snow and write them on the "totals" sheet. You
can then discuss the warnings that might be issued,
e.g. flood warnings for people living near rivers and
transport warnings concerning the snow.
- A modification could be to double the rain or snow
accumulations in hilly areas due to orographic
enhancement, and to explain why this happens.
I've only done this game once and I'm sure it could be
improved, so please let me know if you have ideas or
your experience of trying it yourself.
Part 2: Thunderstorms
The purpose is to give the children a feel for how
thunderstorms work: why air rises in thunderstorms,
how we measure thunderstorms with radar, what a
Doppler radar measures, why tornados form, and how
lightning forms. This was done with the assistance of
several classroom experiments. I didn't do the cloud
in a bottle because they had already seen it, but it
would be easy to slot in here.
Experiment 1: A thunderstorm made of cream
The children will be very impressed with this if it
works. The animation below is for a 40x25x25 cm tank
and the frames are 10 seconds apart:
You need the following equipment (members of the
Department of Meteorology can borrow mine if they
- A clear plastic tank - for 10-15 pounds you can
get one from amazon for keeping pet insects and reptiles.
- Plastic pipettes with a capacity of around 3 ml,
available very cheaply from amazon.
- Five polystyrene cups.
- A kettle.
- A pot of single cream.
- An anglepoise desk lamp.
- A piece of black card and a bulldog clip to
hold it to the back of the tank.
- Optional: glycerine-based food colouring.
- Fill the tank almost to the top with cold tap
water, and clip the black card to the back of the
tank with the bulldog clip.
- Use a pipette to inject 10 ml of single cream into a
puddle at the bottom of the tank of water.
- Support the tank with four upturned cups and
slide a fifth polystyrene cup containing boiling
water under the tank beneath the pool of cream.
The water must be straight out of boiled kettle -
if it comes from a water heater it will be too
cool and the convection will not be very
- Illuminate the tank from above with the
anglepose lamp (this is very important, otherwise
it is much more difficult to see the cloud). The
black card behind will help to give good contrast
when looking in from the front.
- Optional: when the convection has produced a big
anvil cloud and the updrafts are weaker, inject a
pipette full of the glycerine-based food colouring
at the top of the tank near the front. The
audience needs to be watching closely as this will
sink and spread-out at the bottom rapidly - this
represents a downburst and a gust-front.
There are videos on youtube of this experiment
performed with food colouring as the tracer of the
initial convection, but my experience is that this is
not very impressive: firstly, food colouring doesn't
illuminate well so is difficult to see, and secondly
you would need a water based one as the
glycerine-based ones are too dense and sulk and the
base of the tank no matter how much you heat them.
Single cream, on the other hand, has the same density
as water and is very visible. I've also tried milk
and double cream. Milk is a bit too dense, too
optically thin, and looks like small particles rather
than a cloud. Double cream is worth a try at home,
but it is slightly positively buoyant even before you
apply the heat so will start to rise of its own
accord. It is also very optically thick, so produces
impressive cumulus congestus initially but too soon
the tank is completely opaque.
Experiment 2: Radar gun
To demonstrate a Doppler radar working, I bought a
"Bushnell Speedster III" radar gun, which can
measure objects moving at more than 10 mph. Members
of the Department of Meteorology can borrow this
from me if they wish. In class, I got a child to
point it at me with the other children behind it looking
at the readout, while the teacher, who was with
them, threw tennis balls at me and they then
measured their speed. I did it with all the children
behind the gun, rather than getting them to point it
at each other, to avoid complaints from parents
worried about the dangers of microwave radiation;
note that the gun is powered by two C batteries, so
the energy emitted is very small.
In practice the gun looks impressive and the children
(especially boys) want to have a go, but in the end
it just measures a number so is not hugely exciting.
Experiment 3a: Conker on a string
The challenge is to explain how a tornado forms -
the vortex stretching idea is in the slides, and
this comes down to conservation of angular momentum
(but best not to use that phrase). This is simply
and effectively explained with a conker on a string
but with the string also threaded through a piece of
plastic tubing (I used the nozzle cap from a
canister that goes in a sealant gun, and cut the
closed end off) and knotted so that the tubing and
the conker will stay on the string. Hold the
plastic tubing and spin the conker round using the
full length of the string so that the radius of
rotation is large. With your other hand, pull the
string from the back of the tubing so that the
radius of rotation is reduced steadily to zero - the
conker will speed up significantly. The children should
all want to have a go at this. This may help to
explain tornado formation: rising air in the middle
of the cloud stretches any rotation below the cloud,
which sucks the air inwards - this is like the
shortening of the string and it makes the rotation
Experiment 3b: Tornado in a bottle
This is pretty
youtube, but you should expect to find your children
are much more enthusiastic than the ones in this
clip. My tips are:
- Use lots of glitter rather than dye to make
the rotation easily visible
- Don't just remove the caps from the coke
bottles before sticking the bottles together
because the water will go down too quickly and
the tornado will be shortlived. Better to leave
the caps on but cut a circular hole in them
about 1.5 cm in diameter to restrict the flow
and make the tornado last longer. There is a
trade-off, however: if the hole is too small
then even with a lot of swilling by hand you may
find it more difficult to get the tornado to
- The children will want to have a go but younger
groups may well have difficulty getting the
spinning motion needed to start the tornado off.
Experiment 4: Lightning at home
This is also quite well known but is more
difficult to pull-off in a classroom context. I
described here, except that I picked the
aluminium plate up with the pencil before giving
myself a shock. It worked fine at home, but for a
variety of reasons only about a quarter of the
children got a shock:
I've got a disected woolly jacket (from a
charity shop) if anyone in the Department of
Meteorology wants to try, but my advice is that
this is too unreliable to do in a classroom.
- They tended to rup the polystyrene
(styrofoam) plate so hard it sagged in the
middle then was less effective at transfering
its charge to the aluminium plate.
- They all wanted to grab the aluminium
plate quickly, but a shock will only be felt
if the finger is brought to the plate slowly.
- I think many were wearing rubber-soled
shoes which didn't help.