# Connection between emissivity and albedo

• mike133
In summary, the conversation discusses the connection between emissivity and albedo, particularly for opaque objects. It is noted that albedo is a reflection and that the sum of emissivity and albedo is equal to 1. There may also be a spectral weighting involved in the definition of albedo. The conversation also corrects a previous confusion between albedo and absorption and confirms that for non-transparent bodies, emissivity and albedo equal 1.
mike133
Hi,
I am studying thermal radiation. Does anyone know what is a connection between emissivity and albedo.
Regards,
Mike

Albedo is a reflection, so emissivity + albedo = 1, for opaque objects. There's probably some spectral weighting involved in the definition of albedo.

JamesMcKillop
Andy Resnick said:
Albedo is a reflection, so emissivity + albedo = 1, for opaque objects. There's probably some spectral weighting involved in the definition of albedo.
You are confusing emissivity and reflectivity. [No, I'm confusing albedo and absorption. Sorry.]

Emissivity is equal to albedo at a given wavelength. If they were not equal, the heat could flow from colder object to hotter one via radiation.

Last edited:
I think Andy was correct.

For non transparent bodies:
emissivity+albedo=1

Yeah, you're right. I somehow confused albedo and absorption. Emissivity+albedo=1 is correct.

## 1. How does emissivity affect albedo?

Emissivity is a measure of how well a surface emits thermal radiation. Higher emissivity means that a surface emits more thermal radiation, which in turn can affect the temperature of the surface. Albedo, on the other hand, is a measure of the reflectivity of a surface. A higher albedo means that a surface reflects more solar radiation, which can lead to cooler temperatures. Therefore, emissivity and albedo are inversely related.

## 2. What is the relationship between emissivity and albedo?

Emissivity and albedo have an inverse relationship, meaning that as one increases, the other decreases. This is because surfaces with higher emissivity absorb and emit more thermal radiation, while surfaces with higher albedo reflect more solar radiation.

## 3. How do emissivity and albedo affect Earth's climate?

Emissivity and albedo play a crucial role in Earth's climate by influencing the amount of solar radiation that is absorbed or reflected by the Earth's surface. This affects the amount of heat that is trapped in the atmosphere, ultimately impacting global temperatures and the Earth's climate. Changes in emissivity and albedo can contribute to the phenomenon of global warming and climate change.

## 4. Can emissivity and albedo be changed?

Yes, emissivity and albedo can be changed through various factors such as the type of surface, the composition of the surface material, and human activities. For example, painting a surface with a darker color can increase its emissivity, while adding reflective materials such as snow or ice can increase albedo.

## 5. How do scientists measure emissivity and albedo?

Scientists use various instruments and techniques to measure emissivity and albedo. Emissivity can be measured using thermal cameras and spectrometers, while albedo can be measured using radiometers and satellite imagery. These measurements are important for understanding the Earth's energy balance and studying changes in the Earth's climate over time.

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