# Is there a more scientific term for “obstruction of EM waves”?

When EM waves pass through things like rain and hail, they can be "obstructed" and bounced back or absorbed, rather than passing through.

I'm conducting an experiment on this effect, and wondered if there is a more scientific/nerdy way of saying this? I thing obstruction sounds somewhat unprofessional.

Looking in a thesaurus I see interference. I like that better, but it seems very vague. Is there a word that just means absorption or scattering, such that the detector can't detect them?

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This sounds crazy, but I find it can be useful when groping for the right word in scientific writing: go to Google Translate (or Bing or so forth ... insert bad corporate monster least offensive to your worldview here), translate your word into other languages (I find German, French, Italian, Japanese useful) - study the various meanings and also try translating back. Different languages think of things slightly differently, so often one finds inspiration for a precise word amongst all the translations. – WetSavannaAnimal aka Rod Vance Jul 13 '13 at 4:58

Occlusion is a good word that is often used when describing obstruction in the context of geometric optics and is also used in the context of radar in a similar way. Usually it's used for large objects rather than from the sum of many small objects such as rain. But the meaning would probably still be clear.

There's a slight risk of confusion if you're discussion rain and hail because occlusion is also used as meteorological jargon.

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Occlusion. I like that. Thanks :) – DarkLightA Mar 14 '13 at 15:47

Refraction: is specifically the redirection/bending of waves caused by things like changes in density, or material.
Reflection: when the wave returns from the medium it came from.
Scattering: more general, blanket term for any type of change in direction (but not being absorbed).
Absorption: the energy of the waves being absorbed by a material they encounter.

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"Obstruction" is just fine, and it's an acceptable use of jargon. E.g we do say that a nonzero Riemann tensor is an integrability obstruction to the existence of a change of coordinates mapping a generic spacetime to a flat one.

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and a great use of the word "obstruction" (or, I think I mostly says "block" to myself in my head) that one is too. – WetSavannaAnimal aka Rod Vance Jul 13 '13 at 4:52

I'd probably use blocking in this case, but obstruction is fine. Don't use interference! That's something else to do with electromagnetic waves and you don't wanna get muddled.

Remember, you don't always need to use something that sounds super fancy, just use the most descriptive word you can :)

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You should ideally use scattering and absorption when only one of them is present. If both are present (as in rain) then obstruction should be fine, though it is indeed a relatively hand-wavy term (which it has to be: you're unceremoniously dumping together two rather dissimilar phenomena). You might want to rephrase everything in terms of transmission, which is perfectly valid.

Don't use interference, though. This refers to effects coming from coherent mixture of different light beams, and represents a misuse of technical jargon. (Try to avoid thesauri for this kind of thing, too: they will be oblivious to this kind of thing.)

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