Quite right my friend it’s all about convection. Warm water, air, oil, or any liquid/gas stuff will move upwards (rise) when it is heated. Why. Think about it.
Lets think of an experiment (this is a science blog) where we can test this idea and then move on to the question that Hello asked.
You will need a beaker of water, some pencil lead, 3 A batteries, two leads with attached crocodile clips and some food colouring and a dropper
Connect the pencil lead to the batteries using the leads. As the electricity passes through the pencil lead, the pencil lead will heat up. Drop the attached lead into the water. Look carefully at the water, what is happening. If you put a small screen behind the beaker of water and shine a torch on the water you will be able to get a better view of what is happening to the water.
Drop a small amount of food colouring into the water.
Hopefully what you will see are convection currents that have been created by the water close to the lead warming up and beginning to rise. The next question is WHY.
Warning. Do not use mains electricity. It could be very dangerous and kill you.
Why does the water rise?
When the water particles(molecules) come into close contact with the heated pencil lead they gain kinetic energy (see Science Master Special Energy), they move faster. The water molecules spread out so that in any given space there are less water molecules (less dense). This means that gravity comes into action and the colder water can begin to move into the space where the warm water was. The warmer water ‘floats’ on top of the cold water. The cold water then gets warm and and more cold water moves in and the original warm water floats up higher in the beaker. As the warm water rises it gets colder and more dense and eventually will join the column of cold water that is moving (by gravity) downwards toward the hot pencil lead. Wow…..I hope you can see the picture
The movement of the tectonic plates is caused by convection currents and it is this movement that can cause earthquakes. Hopefully when you watch the excellent video below you will see the links.
Hello. If you would like to question anything, please make a comment or ask another question.
(Anyone reading this post who wants to ask a question or make a comment please feel free to do so)