Atmospheric Refractivity

Recommendation P.453

“The Radio Refractive Index: Its Formula and Refractivity Data”

Recommendation P.834

“Effects of Tropospheric Refraction on Radiowave Propagation”

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• Two basic Recommendations dealing with refractivity.

• Rec. P.453 gives the basic formulae and also global maps of refractivity and refractivity gradients. The latest version of Rec also gives other parameters such as duct thickness and duct heights.

• Rec. P.834 addresses how refractivity influences radiowave propagation, e.g.
  • ray bending – which will cause a change in apparent elevation angle to a satellite
  • effective radio path length which differs from the geometrical path length
  • considerations of the conditions governing the entry and exit of energy in ducts.