Y13 Atmosphere Flashcards
Atmosphere define
The thin layer of gas surrounding a planet
Held by gravity
Factors affecting atmosphere size
Gravity
Greater = larger atm
Temperature
Lower temp = greater retention of atmosphere
Presence of a magnetic field
Outline the 4 phases of the history of earth’s atmosphere
Phase 1: earth’s formation
H and He pulled in by grav
Solar winds blow gases away
Phase 2:
Volcanic activity release H2O, CO2, NH3
Phase 3: earth cooled
H2O fell as rain, carrying CO2 to form oceans
Photosynthesis of oceanic algae release O2
UV radiation breaks NH3 into N2 and H2, H2 escapes into space
Phase 4:
Early life converts CO2 to C compounds
What is the soil atmosphere? CO2 content
Extends about 1m into the soil
Bacteria/fungi/plant roots perform respiration, so soil has higher CO2 and lower O2
Difference in conc causes diffusion of gases between soil and atm
5 reasons why the atmosphere is important
Part of the water cycle
Protect against UV
Provides O2 and CO2
Traps heat to create survivable temp
Transfers heat around the earth
What are the 5 layers of the atmosphere?
Closest to furthest:
Troposphere (80%)
Stratosphere (19%) ozone layer here
Mesosphere
Ionosphere / thermosphere
Exosphere (1% total) up to 800km
What is ozone and what does it do?
O3
Absorbs UV
Warms the stratosphere
What makes UV dangerous
UV radiation had energy to break chemical bonds
Ionisation - electrons break away from their atoms
Damage materials / living tissues
types of UV radiation and the ozone layer
Shorter wavelength = more penetrating and dangerous
UV-c most dangerous
Ozone layer absorbs 100% of UV-c and 95% of UV-b radiation
Formation and destruction of ozone via UV light
UV light below 240mm disrupts the bond of the O2 molecule
Forms 2 separate O atoms which join with O2 to form O3
Formation of ozone: UVC absorbed
UV light 240-315nm disrupts the bond of the ozone molecule, converting it back to oxygen
Destruction of ozone: UVB adsorbed
Anthropogenic ozone depletion
CFC molecules used (CFCl3)
UV causes one Cl to break away
Cl pulls O from O3, forming ClO and O2
Free O removes Cl, forms O2
Free Cl repeat cycle
Mesosphere
50km to 80km
Less than 1% of the atmosphere
Meteors burn up
Thermosphere
Contains the ionosphere
X rays and UC radiation absorbed
What factor impacts the height of the troposphere?
7-20km ASL
Widest at the equator and thinnest at the poles
Depends on AIR TEMPERATURE
Colder = particles closer together
Describe the temperature of the layers
Temperature gradient INVERTS at layers
Troposphere - higher, temp DEcrease
Stratosphere - higher, temp INcrease
Mesosphere - higher, temp DEcrease
Thermosphere - higher, temp INcrease