Understanding Thermal Energy and Heat Transfer

Aspect of Weather

HeatHeat refers to

thermal energy and is transferred from one object to another.

How does heat form?…to answer this we must look at The Particle Theory

It states:All matter is made of extremely small particles

(atoms & molecules)

These particles are constantly in motion.

Each substance has particles that are different from those of other substances.

continued….

Particle Theory...Temperature affects the speed of the particles

the higher the temperature is, the faster the particles will move

The state of the substance (solid, liquid, gas) affects the speed of the particles too

solid substances particles move the slowest while gaseous and liquid substances move quicker.

There are three ways heat can be transferred:

These ways are called: “Heat Transfer Methods”(1) Conduction(2) Convection(3) Radiation

(1) Conduction(1) ConductionThe transfer of thermal

energy between two substances (particles) that are in contact.

The energy flow always runs hot to cold until they reach equilibrium.

Conduction takes place between solids.

Example – a cold pot is placed on a hot burner. The heat flows from the burner to the metal pot.

*Metals are the best conductors

(2) Convection(2) Convection The transfer of thermal energy (heat) via currents that move it from one place to another. Within these currents, the warm fluid rise and the cold fluid sinks.

Convection takes place in fluids (gas or liquid)

(3) Radiation(3) RadiationThe transfer of heat via

electromagnetic waves. This is how Earth’

receives energy (heat) from the Sun.

This solar radiation includes visible light, infrared radiation and UV radiation.

Radiation does not need a substance (gas, liquid or solid) to transfer heat.

Electromagnetic radiation

Specific Heat CapacitySpecific Heat CapacityRefers to the amount

of energy (heat) required to raise the temperature of 1.0 g of a substance by 1°C.

Energy (heat) is measured in Joules (J).

1 gram of water requires 4.18J of energy to raise it 1 degree Celsius.

Looking at Table 6.1: Do all substances have the same specific heat capacity?

Let’s review:All matter contains extremely small particles that are in

constant motion.Faster moving particles generate more thermal

energy(heat) and result in a rise in temperature. Slower moving particles generate less thermal energy (heat)

and a drop in temperature. There are three ways heat can be transferred: conduction,

convection, and radiation. Conduction – heat transfer through solids, Convection –

heat transfer through liquids (gas, liquid), Radiation – no substance needed to transfer heat.

It takes a certain amount of thermal energy (heat) to raise a substance one degree celsius – this is known as Specific Heat Capacity.

What does this have to do with weather?Everything!The transfer of thermal

energy (heat) drives atmospheric circulation and weather phenomena!

Your TaskComplete the “How is Heat Transferred?”

Workbook.To be passed in. Finished? Complete the weather components

worksheet.

Quiz – Heat Transfer Methods

Complete questions on looseleaf.

Q1. I just filled an ice cube tray with water and placed it into the freezer. What is going to happen to the speed of the water molecules over time? How will this affect the amount of thermal energy (heat) in the substance?

Q2. They say “a watched pot of water never boils.” I just placed a pot of water on the stove...what is going to happen to the speed of the water molecules over time?

Q3. Which of the following is true of any substance?A) It is made of extremely small particles.B) Its particles are continually in motion.C) It has thermal energyD) It has more thermal energy when its particles are moving faster. E) All of the above.

Q4. Consider the particles shown in the image below. Identify the particles as solid, liquid, or gas.

A B C

Q5. What does this diagram tell you about the relationship between energy(heat) and the state of a substance?

Q6. Which has more thermal energy, a hot cup of tea or one that has cooled for an hour? Explain your reasoning.

Q8. Examine the two cubes – each represents a parcel of air. If the dots represent particles and the arrows indicate the direction and speed, which parcel of air has:(a) more thermal energy (heat)?(b) the higher temperature

Q9. Water turns to ice when the particles are moving so slow that it looses ______ and the temperature drops to ___ ˚C.

Q10. In order for a substance to change from a liquid to a solid state it must (gain/lose) thermal energy.

Q11. In order for a substance to change from a liquid to a gas it must (gain/lose) thermal energy.