- published: 29 Nov 2015
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An adventure is an exciting or unusual experience. It may also be a bold, usually risky undertaking, with an uncertain outcome. Adventures may be activities with some potential for physical danger such as exploring, skydiving, mountain climbing, river rafting or participating in extreme sports. The term also broadly refers to any enterprise that is potentially fraught with physical, financial or psychological risk, such as a business venture, a love affair, or other major life undertakings .
Adventurous experiences create psychological arousal, which can be interpreted as negative (e.g. fear) or positive (e.g. flow), and which can be detrimental as stated by the Yerkes-Dodson law. For some people, adventure becomes a major pursuit in and of itself. According to adventurer André Malraux, in his La Condition Humaine (1933), "If a man is not ready to risk his life, where is his dignity?". Similarly, Helen Keller stated that "Life is either a daring adventure or nothing."
Twilight is the illumination of the Earth's lower atmosphere when the Sun itself is not directly visible because it is below the horizon. Twilight is produced by sunlight scattering in the upper atmosphere, illuminating the lower atmosphere so that the surface of the Earth is neither completely lit nor completely dark. The word "twilight" is also used to denote the periods of time when this illumination occurs.
The further the Sun is below the horizon, the dimmer the twilight (other things such as atmospheric conditions being equal). When the Sun reaches 18 degrees below the horizon, the twilight's brightness is nearly zero, and evening twilight becomes nighttime. When the Sun again reaches 18 degrees below the horizon, nighttime becomes morning twilight. Owing to its distinctive quality, primarily the absence of shadows and the appearance of objects silhouetted against the bright sky, twilight has long been popular with photographers, who refer to it as 'sweet light', and painters, who refer to it as the blue hour, after the French expression: l'heure bleue.