# Opacity of the Earth's atmosphere

• natski
In summary, the conversation is about finding a reliable tabulation of the Earth's atmosphere opacity as a function of wavelength. The person asking the question is looking for a US Standard Atmosphere model or something similar. Some suggestions are given, including LOWTRAN, MODTRAN, HITRAN, and a website with spectroscopy figures. The person asking the question also asks for clarification on the columns in one of the suggested websites.
natski
Hi all,

Does anyone know of a reliable tabulation of the opacity of the Earth's atmosphere (for example at zenith distance zero) as a function of wavelength from 100nm to 1 micron? Obviously the opacity varies with different conditions but something like a US Standard Atmosphere model would suffice for my needs.

Natski

Have you looked at LOWTRAN/MODTRAN/HITRAN?

http://www.stormingmedia.us/73/7334/A733412.html
http://www1.ncdc.noaa.gov/pub/software/lowtran/

Or is something like this good enough:

http://fuse.pha.jhu.edu/~wpb/spectroscopy/figures/trans.gif
http://epsilon.nought.de/tutorials/processing/img2.gif

Last edited by a moderator:
Ah yes this looks very useful, thanks. Looking at http://www1.ncdc.noaa.gov/pub/software/lowtran/lowtran7.16 as an example, there does not seem to be a key as to what the columns actually mean. Do you know what each column represents here?

Natski

Last edited by a moderator:

## 1. What is the opacity of the Earth's atmosphere?

The opacity of the Earth's atmosphere refers to how transparent or opaque it is. It is a measure of how much light can pass through the atmosphere.

## 2. How is the opacity of the Earth's atmosphere measured?

The opacity of the Earth's atmosphere is measured using a unit called optical depth, which is a measure of how much light is absorbed or scattered by the atmosphere. It is typically measured using specialized instruments such as spectrophotometers.

## 3. What factors affect the opacity of the Earth's atmosphere?

Several factors can affect the opacity of the Earth's atmosphere, including the concentration and composition of gases, particles such as dust and pollution, and the angle and intensity of sunlight.

## 4. Why is the opacity of the Earth's atmosphere important?

The opacity of the Earth's atmosphere is important because it plays a crucial role in regulating the Earth's temperature and climate. It also affects how much sunlight reaches the Earth's surface, which is essential for photosynthesis and sustaining life.

## 5. How does human activity impact the opacity of the Earth's atmosphere?

Human activities such as burning fossil fuels, deforestation, and industrial processes can release pollutants and greenhouse gases into the atmosphere, which can increase its opacity and contribute to climate change.

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