What is specific intensity anyway?

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Specific intensity measures the amount of radiation emitted, transmitted, or received in a specific direction, commonly expressed in watts per square meter per steradian (W/m2/sr). The specific intensity of radiation at the solar surface directed toward Earth varies with wavelength and distance, as the sun emits a broad spectrum of radiation. At the Earth's surface, specific intensity is further influenced by atmospheric effects, leading to lower values compared to the solar surface. To calculate specific intensity, relevant equations, such as the Stefan-Boltzmann law, must be applied, considering various factors. Understanding specific intensity is crucial for studying radiative transfer in energy dynamics.
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Hi all,

I need a hand regarding this problem, just can't seem to find the start point. (It's a two parter):

What is the specific intensity of the radiation at the solar surface in the direction of Earth

What is the specific intensity of solar radiation at the surface of the Earth.

As you can see, isn't really specific on values so it would seem you have to quote any used values. Would be great if anyone could help.

ON
 
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e possible explanation of specific intensity is that it is a measure of the amount of radiation (such as light or heat) that is emitted, transmitted, or received in a specific direction. It is a physical quantity that is used in the study of radiative transfer, which is the process of energy transfer through electromagnetic radiation. Specific intensity is typically measured in units of watts per square meter per steradian (W/m2/sr).

To answer the first part of your question, the specific intensity of radiation at the solar surface in the direction of Earth would depend on the wavelength or frequency of the radiation being emitted. The sun emits radiation across a wide range of wavelengths, from infrared to ultraviolet. The specific intensity would also depend on the distance between the sun and Earth, as the intensity of radiation decreases with distance.

For the second part of your question, the specific intensity of solar radiation at the surface of the Earth would again depend on the wavelength and distance. However, it would also be affected by factors such as the Earth's atmosphere, which can absorb and scatter some of the incoming radiation. This is why the specific intensity of solar radiation at Earth's surface is lower than at the solar surface.

To find specific intensity values for these scenarios, you would need to use equations that take into account the relevant variables, such as the Stefan-Boltzmann law for blackbody radiation. It is important to note that specific intensity can vary greatly depending on the specific conditions and context in which it is being measured. I hope this helps clarify the concept of specific intensity for you.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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