Acclimatization

Acclimatization or acclimation is the process of an organism adjusting to change in its environment, allowing it to survive changes in temperature, water and food availability, other stresses and often relates to seasonal weather changes. Acclimatization occurs in a short time, (days to weeks) and within one organism's lifetime (compare adaptation). This may be a discrete occurrence or may instead represent part of a periodic cycle, such as a mammal shedding heavy winter fur in favor of a lighter summer coat. Acclimation is an important characteristic among many organisms because it allows them to evolve over time while changes are also simultaneously occurring in their environment. Organisms adjust their morphological, behavioral, physical, and/or biochemical traits in response to these environmental changes that they are faced with.

There are several effects of high altitude on humans:

The percentage saturation of hemoglobin with oxygen determines the content of oxygen in our blood. After the body reaches around 2,100 m (7,000 feet) above sea level, the saturation of oxyhemoglobin begins to plummet.

Bracketing
In photography, bracketing is the general technique of taking several shots of the same subject using different or the same camera settings. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with a single shot, especially when a small variation in exposure parameters has a comparatively large effect on the resulting image. Autobracketing is automatic bracketing by using a setting on the camera to take several bracketed shots (in contrast to the photographer altering the settings by hand between each shot).

Bracketing, a method for determining range by firing artillery shells both beyond and short of a target.

Bracketing, a method for taking note for features around your base so when you reach one point you will now be able to find your base.

Baseline is a feature that forms a boundary to the area you are traveling in or form a limit that shows you have offshoot your target.
Distance to horizon 6km 3.3 miles when 6ft high on flat ground.
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