NOVEMBER 12, 2015

RIGHT NOW: GET 6.2 NOTES

AGENDA: 6.2 NOTES SKILLS SHEET/HOMEWORK

OBJECTIVE: DETERMINE HOW THE SUN DRIVES ATMOSPHERIC CONVECTION

ATMOSPHERIC HEATING6.2

What happens to solar energy

as it enters our atmosphere?

Let’s find out….

THINK ABOUT IT

Explain how is food heated in an oven….

HOW IS FOOD HEATED IN AN OVEN?

The heating coil heats the air in the oven by radiation and thermal conduction. The hot air circulates by convection and heats up the food and its container. The hot container heats the food by thermal conduction.

Conventional oven

Convection oven

Fan circulates heat more evenly

WHAT HAPPENS TO SOLAR ENERGY ONCE IT ENTERS OUR ATMOSPHERE?

Solar energy is energy from the sun.

This energy from the sun is absorbed by the atmosphere, land, and water and is changed into thermal energy.

Thermal energy is then transferred by

Radiation, thermal conduction, and convection

RADIATION:ENERGY TRANSFER BY WAVES

Earth receives energy from the sun by radiation

Radiation is the transfer of energy as electromagnetic waves

How much energy radiated by the sun reaches Earth?

…..only about two-billionths

CONDUCTION:ENERGY TRANSFER BY CONTACT

Thermal conduction is the transfer of thermal energy through a material.

Thermal energy is always transferred from warm to cold areas.

When air molecules come into direct contact with Earth’s warm surface, thermal energy is transferred to the atmosphere.

DID YOU KNOW?

Although air cannot be seen, our atmosphere has mass and is subject to the physical laws that affect matter.

Air, like water, is a fluid.

A fluid is any material that can flow and takes the shape of its container.

You can visualize wind as air flowing like water.

All fluids move according to specific laws of fluid dynamics.

CONVECTION:ENERGY TRANSFER BY CIRCULATION

Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas.

Most thermal energy in the atmosphere is transferred by convection.

As air is heated, it becomes less dense and rises. Cool air is denser, so it sinks. As cool air sinks, it pushes warm air up. Cool air is heated by Earth’s surface and rises again.

This cycle of warm air rising and cool air sinking causes a circular movement of air called a convection current.

Demonstration of Convection

The water at the bottom of the pot heats up first. This causes it to expand. Since the warmed water has a lower density than the water around it, it risesup through the cooler, dense water.

At the top of the pot, the water cools, increasing itsdensity, which causes it to sink back down to the bottom.

This up and down movement eventually heats all of the water. The continual cycling of fluid is calleda convection current.

Similarly, convection currents in our atmosphere are created as warm air rises and cool air sinks.

*Teacher Demonstrates*Students Observe

PUTTING IT TOGETHER If we place a metal spoon in the pot of boiling

water,

……Will it get hot? Explain why…..

Which process is mainly responsible for effect on the spoon?

Radiation – Thermal Conduction – Convection

Predict what will happen to a wooden spoon placed in the same pot of boiling water.

Explain why…..

SO…SOLAR ENERGY BECOMES THERMAL ENERGY….

WHAT ARE THE THREE WAYS THERMAL ENERGY IS TRANSFERRED?

Radiation, Thermal Conduction, Convection