Solar Radiation Flashcards

Flashcards about Solar Radiation

What range of wavelengths does visible light have?

400 - 700 nm

What is the equation for the speed of light using wavelength and frequency?

Speed = λν, where λ is wavelength and ν is frequency.

What is the equation for the wavenumber?

𝑣𝑣= 1/ λ (cm-1) or 𝑣𝑣= ν / c (cm-1)

What happens in the Photoelectric effect when the frequency of light goes past a threshold?

Current is measured.

What are photons?

Small packets of energy that make up light.

What relationship exists between the energy of a photon and frequency?

The energy of a photon is proportional to the frequency.

What happens to hot things as they get hotter?

They glow brighter.

What type of electromagnetic radiation do cooler objects emit?

Electromagnetic radiation.

At room temperature (20oC), at what wavelength is the maximum intensity of electromagnetic radiation?

Approximately 10 um (infrared).

What is the 'ultraviolet catastrophe'?

The discrepancy between the idealised spectrum of light coming from the sun and the actual spectrum.

What is the approximate temperature of the sun?

~5700 K

What type of radiation does the earth 'shine' in?

Infrared

What is black body radiation?

Black body radiation represents the maximum thermal emission.

Where does the sun have a peak in its spectrum?

About 500 nm.

Where does the earth's irradiance peak?

About 10 um (in the infrared).

What role does black-body radiation play in understanding?

Global warming

What is the Stefan-Boltzmann equation?

𝑬𝑬 = 𝝈𝝈𝑻𝑻𝟒𝟒 where 𝝈𝝈 = 5.7x10-8W m-2K-4

What does the Balanced Flux Model assume?

That the Earth adsorbs all of the solar radiation and then re-radiates it.

What is Albedo?

The fraction of incoming light that is reflected.

What is the average albedo of Earth?

Approximately 0.3

What would the Earth's temperature be if all radiation emitted escaped into space?

About 30 K colder.