## Heat TransferHeating the atmosphere day and nigiht

### Heat transfer

What is heat transfer? Heat transfer is when the energy from a hotter object gets transferred to a cooler object. The word transfer means to move from one place to another so in this instance the energy is being moved from the warm object to the cooler object.

There are three different types of heat transfer. They are conduction, convection, and radiation. They all transfer heat to different objects but they do it in different ways.

#### Molecules

Before the object has heat, the molecules are all compact and tight. They are barely moving. They tend to vibrate. Once the object has heat or is heated up the molecules will then be very spread out. Also they will be moving much faster then before. The colder objects have molecules that are more dense. The warmer objects have molecules that are less dense.

### Types of heat transfer

Conduction is when energy is transferred from the warmer object to the colder object through direct contact. This means that the hot and the cold objects have to be touching in order for the heat to transfer.

If you have ever held a warm cup of coffee, hot chocolate, or tea you have experienced conduction. The energy from the warm drink is being transferred to your hands. This happens because you are touching it.

Convection is when heat is transferred through a liquid or gas. This occurs when there is a difference in temperature. If something has a small density it is usually warm and it will rise. If something has a large density it is usually cold and it will sink. This causes a cycle. The cycle keeps repeating and the object is eventually heated up.

In the ocean the warmer water with rise to the top and the colder water will sink to the bottom. This occurs becuase the warm water is less dense so it rises. The cold water is more dense so it sinks. This cycle keeps on going trying to heat up the ocean.

Radiation is when energy is transferred from the warmer object to the colder object through electromagnetic waves. These are invisible waves that typically have a very high frequency. The warmer object emits the waves out to the cooler object so it heats up.

If you have ever been near a camp fire it heats you up through radiation. The fire will send out electromagnetic waves that reach you and heat up your body.

### How does this relate to the atmosphere?

If there was no sun, the earth would be frozen. Not many people know it but the atmosphere is heated up through heat transfer. The type of heat transfer that is used is radiation.

The sun is transferring energy to earth so it has heat. The way the sun does this is it sends out electromagnetic waves to earth. The earth absorbs most of the waves but it also reflects some of them back into space. (Electromagnetic waves are invisible and tend to have a very high frequency.)

#### Thermal Energy

Thermal energy is when an object is able to do something based on the particles that make it up. For example, ice cream on a cone may be very cold which means it's particles/molecules aren't moving very much and are very packed together. This means the ice cream is able to stay in one shape. If heat is applied to it though then the molecules will become more spread out and they will move faster. This means the ice cream will be able to melt and become a liquid.

When energy is transferred to this ice cream it's thermal energy will determine what it's able to do. If its molecules start to rapidly move and spread out it will turn into a liquid.

### Citations

“The Transfer of Heat Energy.” National Weather Service, www.srh.noaa.gov/jetstream/atmos/heat.html. Accessed 9 Mar. 2017.

“What Is Thermal Energy?-Definition and Examples.” Study.com, 2003, study.com/academy/lesson/what-is-thermal-energy-definition-examples.html. Accessed 9 Mar. 2017.