The Different Types of Twilight, Dawn and Dusk - Deepstash
The Different Types of Twilight, Dawn and Dusk

The Different Types of Twilight, Dawn and Dusk

Curated from: timeanddate.com

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TWILIGHT: Half-light

TWILIGHT: Half-light

  • from Old English twi- ‘two’ (used in an obscure sense) + light (English) = twilight (late middle English)

-OxfordLanguages

  • literally 'second light, half-light'

--wiktionary

Twilight occurs when Earth's upper atmosphere scatters and refracts sunlight which illuminates the lower atmosphere.

The morning twilight is often called dawn , while the evening twilight is also known as dusk .

There are 3 Types of Twilight:

  1. Civil Twilight
  2. Nautical Twilight
  3. Astronomical Twilight

Astronomers define the 3 stages of twilight on the basis of how far the Sun is below the horizon.

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Civil Twilight: Practical Twilight

Civil Twilight: Practical Twilight

“The length of twilight is an element useful to be known: by prolonging the day, it permits the continuance of labor.”

-French physicist Auguste Bravais

Civil twilight occurs when the sun is less than 6 degrees below the horizon

CIVIL DAWN

In the morning it begins when the center of the sun is 6 degrees below the horizon; ends at sunrise

CIVIL DUSK

In the evening, it begins at sunset; ends when the center of the sun is 6 degrees below the horizon

Civil twilight is the brightest form of twilight. There is enough natural sunlight that artificial light may not be required to carry out outdoor activities

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Nautical Twilight

This period is less bright than civil twilight.Artificial light is needed for outdoor activities

Nautical twilight occurs when the center of the sun is between 6 and 12 degrees below the horizon

Nautical dawn is the time when the sun is 12 degrees below the horizon in the morning.

Nautical dusk is when the sun is 12 degrees below the horizon in the evening

"Nutical twilight" has been used since the time when sailors used the stars to navigate, to the today's US military forces' Begin Morning Nautical twilight (BMNT) and End Evening Nautical Twilight (EENT) protocols

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