Atmospheres & Climate

Describe the sources of energy incoming into the Earth system

Solar radiation: 342W/m²; geothermal radiation: 0.6W/m²; anthropogenic energy emissions: 0.2W/m² (Trenberth et al., 2009)

Maximum temperature of the photosphere

5700K (Ahrens, 2017)

Percentage of incoming radiation that is in the visible spectrum

44% (Ahrens, 2017)

Planck’s law definition

Describes the intensity of radiation emitted from a black body at a given temperature for a certain wavelength (hotter objects emit more radiation at smaller wavelengths) (Ahrens, 2017)

Stefan-Boltzmann Law Definition

M (energy per unit area per unit time) = sigma (SB constant) * (temperature)^4 (Bigg, 2012)

Define the Solar Constant

A value of ~1368W/m² defining the total solar energy a unit area at the top of the atmosphere receives, influenced by changes in both the emissivity of the Sun and the amount of energy reaching Earth (Ahrens, 2017)

Define the cycle periods in Milankovitch cycles

Obliquity: 40,000yrs; Precession: 20,000yrs; Eccentricity: 100,000yrs; (Bigg, 2012)

Describe the Faint Young Sun paradox

Early Earth received ~70% of the radiation it does now, despite harboring lots of liquid water. (Goldblatt and Zahnle, 2011)

Describe the effective radiative temperature of Earth and what it is

Accounting for albedo and using the Stefan-Boltzmann law, the expected temperature of the Earth at surface would be -18C, without the influence of the GHE (NASA NSSDC, 2025; Ahrens, 2017)

Describe 3 ways which radiation interacts with matter

transmission: no interaction; scattering: radiation changes direction and nothing more (reflection is a special case of this); absorption: radiation is transformed into heat (Ahrens, 2017)

Describe the greenhouse effect

‘the warming of an atmosphere by its absorbing and emitting infrared radiation while allowing shortwave radiation to pass on through’ (Ahrens, 2017)

Percentage of incoming solar radiation reflected by clouds

20% of incoming solar radiation is reflected by clouds (Trenberth et al., 2009)

Percentage of solar longwave radiation that is trapped within the atmosphere (the greenhouse effect GHE)

90% of surface longwave radiation is trapped within the atmosphere (Trenberth et al., 2009)

How much greater would incoming solar radiation need to be to have the same amount of surface warming without the GHE?

twice as much solar radiation (Herzog, 2025)

How much greater is radiative forcing compared to pre-industrial levels (1750?)

2.29W/m² greater than 1750 (IPCC, 2011)

Percentages of relative substances in the atmosphere

Nitrogen 78.1% (no effect); Oxygen 20.9% (only an active component at the top of the atmosphere) (Ahrens, 2017)

List of active components in the atmosphere

water vapour, carbon dioxide, methane, nitrous oxide, CFCs, clouds, aerosol, ozone (Ahrens, 2017)

Percentage of terrestrial radiation escaping through the atmospheric window

~10% of terrestrial radiation escapes through the atmospheric window (Trenberth et al., 2009)

Which active component is the single largest blocker of terrestrial radiation?

water vapour (Wei et al., 2018)

net radiative forcing of clouds (as a numerical value)

-20W/m² (Quante, 2004)

Examples of positive feedback loops

ice albedo effect: water vapour feedback (warming → increased saturation vapour pressure → increased vapour → enhanced warming)

Examples of negative feedback loops

thermostat effect (more evaporation → more clouds → greater albedo); application of the Stefan-Boltzmann Law (a small increase in temperature → a great increase in emissivity of a black body (the Earth))

What percentage of the solar radiation that reaches the surface causes evapotranspiration?

~50% (Trenberth et al., 2009)

What is the saturation vapour pressure (SVP)

the SVP is the pressure at which air is saturated, dependent on temperature. if this pressure is exceeded, condensation occurs (this creates clouds!); saturation vapor pressure increases with temperature

Example: how does the ocean interact with oscillation systems?

North Atlantic Oscillation (NAO): if the North Atlantic Drift (NAD) is reduced or cooled, latent heat flux near W. Europe reduces and means less storms in Europe; the storm track shifts down accordingly. During 1925-35, the storm track was shifted up, and the UK experienced a wetter than usual climate. (Bigg, 2012)

Heat capacity of water as compared to air

5x (Bigg, 2012)

Proportion of excess longitudinal thermal flux carried by the ocean

~1/3 to ~1/2 (Herzog, 2025)

When does the Indian Summer monsoon occur?

June - September (Ahrens, 2017)

What happens to the Indian Monsoon in El Nino?

It weakens, as a high pressure system exists over the W. Pacific (Ahrens, 2017)

What is the record annual rainfall in Cherrapunji?

2647cm in 1860-61 (Ahrens, 2017)

How many rely on the Indian summer rain?

2bn (Ahrens, 2017)

Ekman transport

Defined as the net movement of water defined by a balance between friction at the surface and Coriolis force, confined to the upper 100m (Bigg, 2012)

Where does thermohaline heat release occur?

3 locations, all in the Atlantic (Herzog, 2025)