Chapter 2 part B Flashcards
What is the main reason greenhouses hot?
Greenhouses are hot mainly because heat is trapped by the lid at the top (no convection to atmosphere above)
How does solar radiation affect the temperature in greenhouses?
Solar radiation absorbed but heat is unable to “vent” upward (no convection to atmosphere above)
Greenhouse VS Atmospheric greenhouse effect
Why are “greenhouse” gasses considered selective absorber?
“Greenhouse” gases are generally poor shortwave absorbers but good longwave (infrared light) absorbers
Where does O3 absorb best?
O3 absorbs best in UV
(Ozone “layer” in stratosphere)
How is IR radiation able to escape to space?
Two “atmospheric windows” between 8 –13 μm
Why are certain substances greenhouse gases and others are not (ex: molecular oxygen (O2) and nitrogen (N2))?
Molecular properties of tri-and multi-atomic gases allows for stretching and bending vibrations in the “right” wavelength range for infrared (longwave) absorption
(ex: H20)
Why is the albedo of thick clouds higher?
How do thick clouds look compared to thin clouds?
What would happen if equator to pole heat transfer was not steadying climate?
equator would forever heat up and the polar regions would cool.
Is IR radiation reflected?
IR radiation is not reflected but is absorbed and re-emitted by the atmosphere
Are all greenhouse gases equally efficient at absorbing LW radiation (on per-molecule basis)? → Global warming potential?
What reflection / transmission / absorption properties depend are related to a cirrus type of cloud?
thin, high-altitude (cold) clouds, effectively transmit shortwave but absorb some infrared radiation (enhances greenhouse effect)
What reflection / transmission / absorption properties depend are related to low-altitude clouds ?
e.g.stratocumulus): more scattering/reflection of shortwave and longwave radiation. Re-emission temperature (of clouds) closer to that of surface temperature
What is electromagnetic radiation (EM) and what causes it?
EM radiation is emitted by all objects warmer than absolute zero (T > 0 K). It is caused by the random vibrations of electrons and other charged particles and propagates as electromagnetic waves or photons.
What is the relationship between wavelength (λ), frequency (f), and phase speed (v)?
They are related by the equation: v = f × λ. For electromagnetic waves, phase speed is the speed of light (c ≈ 3.0×10^8 m/s). Therefore, λ = c/f and f = c/λ.
What is radiant energy per photon and how is it calculated?
Radiant energy per photon is calculated using the equation RE = h × c/λ, where h is Planck’s constant (6.626 × 10⁻³⁴ J·s), c is the speed of light, and λ is the wavelength
How does wavelength relate to frequency and energy?
Higher frequency corresponds to a shorter wavelength and higher energy, while lower frequency corresponds to a longer wavelength and lower energy.
What is a black body, and how does it differ from a white body?
A black body is an idealized object that absorbs all incident electromagnetic radiation and emits the maximum energy possible at its temperature. A white body, on the other hand, reflects all incident radiation uniformly in all directions.
What is the Stefan-Boltzmann law and how does it relate to temperature?
The Stefan-Boltzmann law states that the total radiant energy emitted by a black body per unit time per unit area is proportional to the fourth power of its absolute temperature (T): E = σT⁴, where σ is the Stefan-Boltzmann constant (5.67×10^−8 W m^−2 K^−4).
What does Wien’s Displacement Law describe?
Wien’s Law describes the relationship between the peak wavelength (λmax) of radiation emitted by a black body and its absolute temperature (T): λmax = const./T, where the constant is 2897 μm·K.
How do the Sun and Earth differ in terms of radiation?
The Sun emits shortwave (SW) radiation with a peak wavelength around 0.5 μm (green light), while the Earth emits longwave (LW) radiation with a peak wavelength around 10 μm (infrared).
What is Rayleigh scattering and why is the sky blue?
Rayleigh scattering occurs when light is scattered by particles much smaller than its wavelength. Shorter wavelengths (blue light) are scattered more effectively than longer wavelengths, making the sky appear blue.
What is albedo, and how does it vary with surface types?
Albedo is the fraction of incident shortwave radiation reflected by a surface. Snow has a high albedo (reflects up to 95%), while water bodies absorb up to 98% of radiation, depending on the angle of incoming light.
