Horizon - Distance To The Horizon

Distance To The Horizon

Ignoring the effect of atmospheric refraction, distance to the horizon from an observer close to the Earth's surface is about

where d is in kilometres and h is height above ground level in metres.

Examples:

• For an observer standing on the ground with h = 1.70 metres (5 ft 7 in) (average eye-level height), the horizon is at a distance of 4.7 kilometres (2.9 mi).
• For an observer standing on the ground with h = 2 metres (6 ft 7 in), the horizon is at a distance of 5 kilometres (3.1 mi).
• For an observer standing on a hill or tower of 100 metres (330 ft) in height, the horizon is at a distance of 39 kilometres (24 mi).
• For an observer standing at the top of the Burj Khalifa (828 metres (2,717 ft) in height), the horizon is at a distance of 111 kilometres (69 mi).

With d in miles and h in feet,

Examples, assuming no refraction:

• For an observer on the ground with eye level at h = 5 ft 7 in (5.583 ft), the horizon is at a distance of 2.9 miles (4.7 km).
• For an observer standing on a hill or tower 100 feet (30 m) in height, the horizon is at a distance of 12.2 miles (19.6 km).
• For an observer on the summit of Aconcagua (22,841 feet (6,962 m) in height), the sea-level horizon to the west is at a distance of 184 miles (296 km).