7th grade Ch. 1 Sec. 2 Convection Currents & the MantlePresentation Transcript
Ch. 1 Sec. 2 Convection & the Mantle YouTube video-Bill Nye Heat
movement of energy from warmer object cooler object
3 types :
1. radiation thru. empty space no direct contact 2. conduction by direct contact 3. convection movement of a heated fluid (liquids & gases)
flow that transfers heat within a fluid
When a fluid is heated, its density decreases.
When a fluid cools, its density increases.
changes in a fluid’s density force of gravity heating & cooling of a fluid
Convection in Earth's Mantle Heat from Earth’s core & mantle cause convection currents to form in asthenosphere Hot columns of mantle rise thru asthenosphere At top of asthenosphere, hot material spreads out Pushes cooler material out of way Cooler material sinks back into asthenosphere
A lava lamp demonstrating
convection in the mantle.
examples of heat transfer conduction
Convection & Conduction
In conduction, the heated particles of a substance transfer heat to other particles through direct contact.
Heat goes higher .
Hot air, hot water, and hot rock
all tend to rise.
Cold creeps lower.
Cold air, cold water, and cool rock
all tend to sink.
Were you paying attention ???
What are the three types of heat transfer?
Describe how convection currents form.
The heating and cooling of a fluid
Changes in a fluid’s density
Force of gravity combine to set convection currents in motion
What happens to convection currents when a fluid reaches a constant temperature?
When a fluid reaches a constant temperature, the convection currents stop.