Lectures part 1
01 December 2020 16:59
By Z. Floren
2020-2021
Natural Processes Page 1
,Lecture 1 - 09/11/20
09 November 2020 09:07
Energy in the Atmosphere
Surface -> troposphere -> stratosphere
Troposphere = decline T in height as warm air rises and cools down. Much mixing in troposphere
(most important for humans; most linked to the terrestrial atmosphere)
Stratosphere = quit stable layer, hardly any mixing
Troposphere ends in Tropopause (almost no change in T)
Atmospheric composition of dry air:
• Mostly N2 and O2
• Methane (CH4) and hydrogen (H2) important too but in small amounts
○ Hydrogen is in the atmosphere shortly as it rains down
What happens to CO2 in the atmosphere?
It is not accumulating, because we would have been suffocated by now if this is the case. CO2 is
taken up by vegetation for photosynthesis (20-30%), taken up by the ocean (25%). The long-term
CO2 cycle includes chemical weathering.
Energy
The intensity of radiation is related to the wavelength
- The shorter the wavelength the higher the intensity of the radiation ( -> the more energy)
- Depends on temperature
See Wien's law: λmax= in nm
• The sun is hot enough the emit short-wave radiation
• All objects on Earth emit long-wave radiation
• All objects above 0° Kelvin release radiation
• E=έσT^4
○ έ=emissivity, blackbody έ = 1
○ Σ = Stefan-Bolzman constant (5,67*10^8)
Types of radiation:
• Short-wave radiation
○ Can be reflected according to the albedo of an object
○ Emitted by the sun
▪ Reflected by the clouds & the Earth's surface
▪ Absorbed by the atmosphere, the biosphere and the Earth's surface
□ Biosphere will heat up
• Long-wave radiation
○ Emitted by the surface (because every object that has a certain T emit radiation)
○ GHG absorbs the energy and re-emits it in all directions, but most energy is re-emitted in
the direction to the Earth's surface
▪ Atmosphere will also re-emit long-wave radiation
□ T troposphere decreasing by hight, so the emitted radiation is lower when
we get higher in the atmosphere than lower in the atmosphere (purely
depended on the T on the location)
Incoming energy
Experiences:
• Reflection
○ Albedo
○ Only with short-wave radiation
• Scattering
○ Insolation will be scattered by aerosols in the atmosphere, part will be scattered out of
the atmosphere
○ Only short-wave radiation
• Absorption
Both long-wave and short-wave radiation
Natural Processes Page 2
, ○ Both long-wave and short-wave radiation
• Re-emission
○ Both long-wave and short-wave radiation
Albedo
Albedo = percentage of short-wave radiation reflected
Energy fluxes
Natural Processes Page 3
, Energy fluxes
Energy lost = long-wave radiation lost + sensible heat lost + latent heat lost
Amount of radiation
Depends on:
• Inverse square law
○
○
• Earth's axis
○ Depends on the seasons
○
Natural Processes Page 4
01 December 2020 16:59
By Z. Floren
2020-2021
Natural Processes Page 1
,Lecture 1 - 09/11/20
09 November 2020 09:07
Energy in the Atmosphere
Surface -> troposphere -> stratosphere
Troposphere = decline T in height as warm air rises and cools down. Much mixing in troposphere
(most important for humans; most linked to the terrestrial atmosphere)
Stratosphere = quit stable layer, hardly any mixing
Troposphere ends in Tropopause (almost no change in T)
Atmospheric composition of dry air:
• Mostly N2 and O2
• Methane (CH4) and hydrogen (H2) important too but in small amounts
○ Hydrogen is in the atmosphere shortly as it rains down
What happens to CO2 in the atmosphere?
It is not accumulating, because we would have been suffocated by now if this is the case. CO2 is
taken up by vegetation for photosynthesis (20-30%), taken up by the ocean (25%). The long-term
CO2 cycle includes chemical weathering.
Energy
The intensity of radiation is related to the wavelength
- The shorter the wavelength the higher the intensity of the radiation ( -> the more energy)
- Depends on temperature
See Wien's law: λmax= in nm
• The sun is hot enough the emit short-wave radiation
• All objects on Earth emit long-wave radiation
• All objects above 0° Kelvin release radiation
• E=έσT^4
○ έ=emissivity, blackbody έ = 1
○ Σ = Stefan-Bolzman constant (5,67*10^8)
Types of radiation:
• Short-wave radiation
○ Can be reflected according to the albedo of an object
○ Emitted by the sun
▪ Reflected by the clouds & the Earth's surface
▪ Absorbed by the atmosphere, the biosphere and the Earth's surface
□ Biosphere will heat up
• Long-wave radiation
○ Emitted by the surface (because every object that has a certain T emit radiation)
○ GHG absorbs the energy and re-emits it in all directions, but most energy is re-emitted in
the direction to the Earth's surface
▪ Atmosphere will also re-emit long-wave radiation
□ T troposphere decreasing by hight, so the emitted radiation is lower when
we get higher in the atmosphere than lower in the atmosphere (purely
depended on the T on the location)
Incoming energy
Experiences:
• Reflection
○ Albedo
○ Only with short-wave radiation
• Scattering
○ Insolation will be scattered by aerosols in the atmosphere, part will be scattered out of
the atmosphere
○ Only short-wave radiation
• Absorption
Both long-wave and short-wave radiation
Natural Processes Page 2
, ○ Both long-wave and short-wave radiation
• Re-emission
○ Both long-wave and short-wave radiation
Albedo
Albedo = percentage of short-wave radiation reflected
Energy fluxes
Natural Processes Page 3
, Energy fluxes
Energy lost = long-wave radiation lost + sensible heat lost + latent heat lost
Amount of radiation
Depends on:
• Inverse square law
○
○
• Earth's axis
○ Depends on the seasons
○
Natural Processes Page 4
