Colourful Convection Currents

Our experiment today is Colourful Convection Currents.

Convection is one of those words that we often hear used, but we may not completely understand its meaning. Weather forecasters show how convection currents are formed when warm and cold air masses meet in the atmosphere. Convection currents are responsible for warm water currents that occur in oceans. This activity demonstrates convection currents in a very colorful fashion.

Materials
Four empty identical bottles (mouth of the bottle should be at least 1 1/2 inches in diameter) or use our Split Demo Tank
Access to warm and cold water
Food colouring
3 x 5 inch index card or an old playing card

Procedure

Fill two bottles with warm water from the tap and the other two bottles with cold water. Use food coloring to color the warm water yellow and the cold water blue. Each bottle must be filled to the brim with water.

Hot over cold: Place the index card or old playing card over the mouth of one of the warm water bottles. Hold the card in place as you turn the bottle upside down and rest it on top of one of the cold water bottles. The bottles should be positioned so that they are mouth to mouth with the card separating the two liquids. You may want to do this over a sink.

Carefully slip the card out from in between the two bottles. Make sure that you are holding onto the top bottle when you remove the card. Observe what happens to the colored liquids in the two bottles.

Cold over hot: Repeat steps 2 and 3, but this time place the bottle of cold water on top of the warm water.


The movement of warm and cold water inside the bottles is referred to as the convection current. In our daily life, warm currents can occur in oceans, like the warm Gulf Stream moving up north along the American Eastern Seaboard. Convection currents in the atmosphere are responsible for the formation of thunderstorms as the warm and cold air masses collide.

[Source from: http://www.stevespanglerscience.com/lab/experiments/colorful-convection-currents]