Here is the current term:If below it different substantially compared to how it appears in your app/software, be sure to update your software/app's content prior to using this form.
Twilight
The intervals of incomplete darkness following sunset and preceding sunrise. The time at which evening twilight ends or morning twilight begins is determined by arbitrary convention, and several kinds of twilight have been defined and used; most commonly civil, nautical, and astronomical twilight.
Civil Twilight-The period of time before sunrise and after sunset when the sun is not more than 6° below the horizon.
Nautical Twilight-The period of time before sunrise and after sunset when the sun is not more than 12° below the horizon.
Astronomical Twilight-The period of time before sunrise and after sunset when the sun is not more than 18° below the horizon.
source: FAA Aviation Weather for Pilots (AC 00-6A)
Please do not use this form to tell us that the definition you saw doesn't necessarily match the context where you saw it. We use an automated keyword-based system to match the tens of thousands of definitions in our glossaries with our material. Sometimes, when a term has more than one meaning or use or when an abbreviation might stand for more than one thing or resemble a 'normal' word, this results in a definition for a term being shown that doesn't necessarily match the context. Please do not report such issues here. Rather, please use your best judgment to evaluate whether such definitions apply to what you're reading. If the answer is 'no' but nevertheless you feel the term doen't have a good definition in our system but should, please go back and find the 'suggest a term' link in the app. Thanks!
We welcome your feedback.Please carefully fill out the specifics below. If you wish to comment on more than one term/definition, please fill out and submit this form separately for each.
Specifics:
Please Identify Yourself.It's important, so that we can get back to you with feedback or requests for clarification.
Name
E-Mail
Please enter your email address above solely for the purpose that our editorial team might, if necessary, contact you with questions, comments, or requests for clarification.