Chapter 2 - Energy Flashcards
How does the average speed (motion) of air molecules relate to the air temperature?
Cold air = molecules have a low average speed
Warm air = molecules have a high average speed
What is the difference between temperature and heat?
Energy = The ability or capacity to do work on some form of matter. Temperature = measure of the average speed (kinetic energy) of the atoms and molecules.
What is conduction? (In earth’s atmosphere)
The transfer of heat from molecule to molecule within a substance. Always flow from warmer to colder regions. Air is a poor conductor of heat.
What is convection? (In earth’s atmosphere)
The transfer of heat by the mass movement of a fluid (such as water and air). Certain areas of earth’s surface absorb more heat from the sun than others. Gains extra heat by conduction. Expands and rises. Cold air replace this air. Creates a vertical exchange of heat.
What is advection?
Horisontal convection (moving air, wind).
What is radiation? (In earth’s atmosphere)
The energy transfered from the sun. Travels in the form of waves and release energy when absorbed my an object. Earth absorbs solar radiation during daylight hours and emits infrared radiation day and night.
Is the earth or the atmosphere a better absorber/emitter of radiation?
Earth. It behaves like a black body.
How does the temperature of an object influence the radiation that it emits?
The higher the temperature, the shorter are the wavelengths of the emitted radiation.
If Earth’s surface continually radiates energy, why doesn’t it become colder and colder?
The surface also absorbs energy. During the day it absorbs more than it emits –> warmer. During the night it emits more than it absorbs –> colder.
What is albedo?
The percentage of radiation returning from a given surface compared to the radiation initially striking the surface.
What processes contribute to earth’s albedo being 30%?
4 % - Reflected from earth’s surface, 20 % - Reflected from clouds (albedo 60%!), 6 % - Scattered by atmosphere.
How much of the radiation is absorbed by earth and the atmosphere/clouds?
51 % - surface, 19 % - atmosphere/clouds
At night, why do materials that are poor heat conductors cool to temperatures less than the sourrounding air?
It depends on the density and conductivity of an object (inversion). The ground for example is a better heat conductor than the air, hence it cools down faster during night. Hence we get colder air at the ground (inversion) in the early morning.
In northern latitudes, the oceans are warmer in summer than they are in winter. In which season do the oceans lose heat most rapidly to the atmosphere by conduction?
winter even though the oceans are cooler because there is a bigger temperature contrast.
in conduction processes, heat always travels from warmer to colder regions. Therefore, more heat would be lost in the winter.
Why must you stand closer to a small fire to experience the same warmth you get when standing farther away from a large fire?
small fire = less energy. The energy emits outward in a sphere so the smaller the fire the closer you have to stand.
