Lesson 4.1 - Heat Transfer in Nature

What's it like outside right now?  Is it sunny, cloudy, raining, snowing, windy, hot, or cold?  The weather is affected by heat transfer.  By the end of this lesson, you will have learned how this happens. 

Read Heat Transfer in Nature and Investigation 5C Heat Convection in Liquids and Gases: Teacher Demonstration up to Part 2 on pages 92 and 93 in your textbook.

Then, complete the following questions.

Question 1. What causes wind? 

Question 2. Write a prediction for Part 1: Observe Convection in a Liquid of this investigation.

Then, return here to continue this lesson.

 

 

Now view the demonstration of convection currents.

Question 3. What happened to the crystals of potassium permanganate when they were dropped into the water?

Question 4. Explain how convection currents in liquids transfer heat.

Then, return here to continue this lesson.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What causes wind? 

Wind is caused by convection in the air (atmosphere).

Question 2. Write a prediction for Part 1: Observe Convection in a Liquid of this investigation.

The food colouring should disperse throughout the water.  You may have known that it will rise above the hot plate area, move towards the cold area, and then drop down before moving back to the hot plate area. 

 

Click to return to where you left off in this lesson.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 3. What happened to the crystals of potassium permanganate when they were dropped into the water?

The crystals of potassium permanganate dropped straight to the bottom of the water.  Then, they began to dissolve, turning the water into a blue-coloured solution.  The appearance of the solution was coloured, wispy, threads.  These moved upwards and spread out thinner as they moved.  The motion was initially a small circle; later, the circle grew larger until the entire tank was involved.

Question 4. Explain how convection currents in liquids transfer heat.

The heated liquid is less dense than the colder liquid.  It rises and is replaced by the colder, more dense liquid.  The heat is transferred throughout the liquid by the continual heating of the liquid at one location and the heated liquid being replaced by colder liquid.  This movement is called convection currents.

Put another way, convection currents transfer heat by moving heated liquid upwards and replacing it with cold liquid that is then heated.  The cycle continues and the liquid moves in a circular pattern.


Go to the next page to continue Lesson 4.