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Climate Change classes 1
UQ 3 May 07 Cars and ozone
UQ 2 Mar 07 Urban air
F: Coffee in the wind
F: Sources and sinks
R: Pathways of air
R: Kerbside measurements
A: flour powder experiment
A: Questions and experiments
C: Information for teachers
Climate change 2007 IPCC special
UQ 1 Nov Dec 06 Particles in air
Special: Oct. 2006 Communication
Nr 10 Sept. 2006 Africa's emissions
Nr 9 July 06 Air traffic
Special: June 06 Climate summit
Nr 8 April 2006 Ozone & N2 cycle
Nr 7 March 2006 Climate modeling
Nr 6 Feb. 2006 acid rain
Nr 5 Jan. 2006 oceanic sulfur
Special: Nov 05 Ozzy Ozone
Nr 4 Oct. 2005 light/satellites
Special: Sept 05 Cyclones
Nr 3 Sept. 2005 methane/energy
Special: July 05 Greenhouse Earth
Nr 2 June 2005 forest/aerosols
No 1 May 2005 vegetation/CO2
     
Activities

Flour powder experiment

Particulate matter sometimes blurs the air and reduces the visibility. However, apart from sandstorms and big fires the particles themselves are usually not visible, because they are by far smaller than 100 µm. Therefore we hardly notice the transport of particles in our environment.
  

Idea and approach

Flour can be used as a simple source of particles in order to demonstrate how they are carried through the air driven by wind and air streams. Dispersed flour powder generates particles which are sufficiently large in order to be seen but also sufficiently light in order not to sink immediately to the ground.
We would like to observe how the dust is carried in the air.
  

Animation flour dust

1. Cutout from the setup with and without raised flour dust.

Material

table with rolls or high roll car (e.g. mobile laboratory table)
tarpaulin
black cardboard
stones
several barriers made from plastic or other washable material
extension cable
multiplug connector
hair dryer
a few tablespoons of flour
  

flour and hair dryer

2. The tools: tarpaulin, flour and hair dryer

Preparation

The rolling car is moved to the schoolyard. Dry weather and moderate wind might be ideal conditions for the experiment. We spread out the tarpaulin over the table and install a few barriers (10 - 50 cm height). The barriers may be put on the tarpaulin or be hidden under it. We put three discs from the black cardboard (diameter about 30 cm) on the ground and pin it down with a stone.
We put the plug of the hair dryer into the multiplug connector (extension cable).
About one tablespoonful of flour is put on the tarpaulin, so that it can be blown in the wind direction over the barriers.
 

Experiment

We orientate the air stream of the hair dryer in wind direction and bring it slowly closer to the flour, until the powder starts to be dispersed in the air.
We observe the dispersion before and behind the barriers.
We can see on the black cardboard on the ground, how far detectable amounts of flour are carried through the air. But we need to consider that particles are also formed and transported which are too fine to be seen or detected.
  

setup with tarp

3. Flour powder is raised by the hair dryer.

flour powder

Overview of all questions and experiments

 

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last updated 20.08.2007 | © ACCENT - Atmospheric Composition Change 2013