P8.2 Powering Earth Flashcards
2 types of seismic waves
P (primary) waves and S (secondary) waves
P waves
Longitudinal
Fast (5 km/s)
Can go through solids and liquids
S waves
Transverse
Slower (3 km/s)
Can go through solids only
Shadow zones
Where one or both types of waves are not detected
Proof that Earth has a liquid outer core
Lack of propagation of S waves (shadow zones for S waves are present)
Type of EM radiation stars emit
All but mainly visible light
It is a black body meaning it emits and absorbs every wavelength of EM radiation
Relationship between temperature and wavelength
The hotter an object, the shorter wavelength peak it has
What colour will hotter stars and cooler stars emit
Hotter - blue
Cooler - yellow and red
3 main greenhouse gases
Carbon dioxide
Methane
Water vapour
How greenhouse gases are NATURALLY released into the atmosphere
Volcanoes (CO2)
Respiration (CO2)
Oceans evaporating (H2O as steam)
How greenhouse gases are released into the atmosphere due to HUMAN ACTIVITY
Combustion of fossil fuels (CO2)
Deforestation (CO2)
Extensive cattle farming (CH4)
Explain greenhouse effect
Short wavelength visible light passes through the atmosphere mainly unobstructed
Some reflects from clouds
Earth absorbs the radiation and heats up
It is warm enough to emit only long wavelength infrared radiation
Infrared radiation is absorbed by greenhouse gases in the atmosphere
This heats the atmosphere
IR radiation absorbed by the atmosphere is then re-emitted in all directions
Some is emitted back to the Earth’s surface
Force which works on all planets around the sun
Centripetal force
This force always acts towards the centre of the orbit
The force/acceleration must be at right angles to the direction of movement
The velocity is changing because the direction is changing, but the speed is constant
Why are planets closer to sun able to move faster than objects away from sun
Since they are closer, they have a larger force of gravity working on it as it’s closer to the sun and likewise with the opposite according to the inverse square law
Geostationary orbit satellites
Take 24 hours to orbit
Remain in fixed position above Earth’s surface
Orbit above Earth’s equator
Used for satellite communication