General formula for refractive index of moist air?

In summary, the conversation is about finding a formula or tables to determine the trajectory of a photon through a cloud with varying temperature, pressure, and humidity. While Wolfram Alpha may provide some values and a formula for moist air, it may not be relevant for the problem as a cloud is not just moist air but also has small droplets of water that affect the photon's trajectory. The changes in index with humidity are also minimal.
  • #1
mikeph
1,235
18
Not sure if one exists but can anyone point me in the right direction?

Looking for a formula which includes the temperature and partial/total pressure dependencies? I'm trying to find the trajectory of a photon through a cloud of varying (but known) temperature, pressure and humidity.

If there is no formula are there tables?

My search has so far found very little. Looking at infra-red/visible frequencies.

Thanks.
 
Science news on Phys.org
  • #2
Wolfram Alpha provides the values for moist air so there is some formula I suppose.
Just Google "index refraction moist air".
However, I am afraid you may be looking for data that is not relevant for your problem.
A cloud is not moist air but air with small droplets of water in suspension. The photon will suffer scattering on the dropplets and this may be the main mechanism to determine the trajectory.
If you are really interested in moist air, the changes of index with humidity are quite negligible.
 

1. What is the general formula for refractive index of moist air?

The general formula for refractive index of moist air is n = 1 + (77.6 x P)/(273 + T), where n is the refractive index, P is the partial pressure of water vapor, and T is the temperature in degrees Celsius.

2. Why is the refractive index of moist air important for scientists?

The refractive index of moist air is important for scientists because it affects the propagation of light through the atmosphere. This is especially important for remote sensing and atmospheric studies, as well as for the accuracy of measurements in optical instruments.

3. How does the refractive index of moist air change with temperature and pressure?

The refractive index of moist air increases with both temperature and pressure. As the temperature increases, the air becomes less dense and the refractive index decreases. However, the presence of water vapor in the air increases the refractive index. Similarly, an increase in pressure causes an increase in density and therefore an increase in refractive index.

4. What factors affect the accuracy of the general formula for refractive index of moist air?

The accuracy of the general formula for refractive index of moist air can be affected by several factors. These include changes in air composition, such as varying levels of pollutants or other gases, as well as changes in humidity and temperature. Additionally, the formula assumes ideal conditions and may not accurately represent real-world situations.

5. Can the general formula for refractive index of moist air be used for all types of air?

No, the general formula for refractive index of moist air is specifically designed for moist air, which contains water vapor. It cannot be used for dry air, which has a different refractive index, or for other types of air with varying compositions. Additionally, the formula may not be accurate for extreme temperatures or pressures.

Similar threads

Replies
4
Views
2K
Replies
3
Views
743
Replies
7
Views
539
Replies
1
Views
2K
Replies
1
Views
2K
  • Classical Physics
Replies
13
Views
9K
  • Introductory Physics Homework Help
Replies
3
Views
3K
Back
Top