When do you see the curvature of the earth

Cold weather raises the atmospheric refraction making it possible for people in colder regions to see further. Secondly, clouds hover above the ground level and can be seen further than the surface. As much as the weather aids our view, it can also distort it.

Precipitation and fog scatter light, making it impossible to see features visible on a clear day. There are thousands of photographs on the internet of people claiming to have photographed the curvature of the Earth. Scientists have dismissed these photographs as fake or misrepresented.

In almost every scenario, the curvature is caused by the distortion of the camera lens. If one lifts a camera above the center of the frame, then the right and left edges curve inwards to mimic Earth's curvature. The Earth curves at about 8 inches for every mile squared, but this distance is too minimal for a human being to discern the curvature. So, how high do you have to be to see the curvature of the Earth? Technically, you can see the curvature of Earth even at sea level. Even the ancient Greeks knew that the Earth is round: a ship on the horizon moving toward the viewer will gradually appear with the masts first, followed by the superstructure, then the hull.

From just 3 meters 10 feet above the surface, you can see the horizon 6. This is one of the reasons why, at least from the sixth century BC, ancient civilizations understood that the Earth was curved, not flat. Earth is big. Visual daytime observations show that the minimum altitude at which curvature of the horizon can be detected is at or slightly below 35, feet 10, meters — about the cruising altitude of a passenger aircraft , providing that the field of view is wide 60 degrees and nearly cloud-free.

Your email address will not be published. My pictures, taken with a 30x optical zoom camera. The part of the boat that is missing in the left image is hidden by the quasi-spherical shape of the Earth. In fact, if you would know the size of the boat and its distance, we could infer the radius of the Earth.

But since we already know this, let's do it the other way around and deduce the distance to which we can see the full boat:. The plot is like this:. Distance of visibility d vertical axis, in km , as a function of the elevation h of the observer above the sea level horizontal axis, in m. From just 3 m above the surface, you can see the horizon 6. If you are 30 m high, then you can see up to 20 km far away.

This is one of the reasons why the ancient cultures, at least since the sixth century BC, knew that the Earth was curved, not flat. They just needed good eyes. You can read first-hand Pliny 1st century on the unquestionable spherical shape of our planet in his Historia Naturalis. Cartoon defining the variables used above. But addressing more precisely the question. This results in this dependence between gamma vertical axis and h horizontal axis :. Angle of the horizon below the flat-Earth horizon gamma , in degrees, on the vertical axis of this plot as a function of the observer's elevation h above the surface meters.

Note that the apparent angular size of the Sun or the Moon is around 0. So, at an altitude of only m above the sea level you can already see 60 km far and the horizon will be lower than normal by the same angular size of the sun half a degree. While normally we are no capable of feeling this small lowering of the horizon, there is a cheap telescopic device called levelmeter that allows you to point in the direction perpendicular to gravity, revealing how lowered is the horizon when you are only a few meters high.

When you are on a plane ca. And you can see under ideal meteorological conditions to a distance of km. Felix Baumgartner roughly doubled this number but the pictures circulated in the news were taken with very wide angle, so the ostensible curvature of the Earth they suggest is mostly an artifact of the camera, not what Felix actually saw.

This ostensible curvature of the Earth is mostly an artifact of the camera's wide-angle objective, not what Felix Baumgartner actually saw. A quick Google turned up a published article answering precisely this question Lynch, The abstract states:. Reports and photographs claiming that visual observers can detect the curvature of the Earth from high mountains or high-flying commercial aircraft are investigated.

Photographs purporting to show the curvature of the Earth are always suspect because virtually all camera lenses project an image that suffers from barrel distortion.

To accurately assess curvature from a photograph, the horizon must be placed precisely in the center of the image, i. Note that the given minimum of 35, feet Lynch, D. Visually discerning the curvature of the Earth. Applied Optics , 47 34 , HH It's hard to see the curvature of the earth from an altitude of 7 miles or 37, ft typical cruising altitude of a jetliner but easy to see from miles typical altitude of the ISS.

That's only about 3. From the ISS at miles, the line of sight is 1, miles, which covers about Most people don't realize how large the earth is compared to the altitude of a passenger aircraft.

It's easy to think we're really high up, but comparatively we're just skimming the surface. The attached drawing is to scale, but the images of the jetliner and ISS are NOT to scale much, much larger than their actual sizes. Further to DrGC's excellent answer, a subjective assessment of visibility of the Earth's curvature can be gleaned from pilot's experioence over many decades.

These can be summarized as:. High up on a peak in Hawaii surrounded by nothing but water in every direction, seeing the curvature can be really quite humbling. As far as the boat theory goes, its not something I'd be able to use considering Im aware of the unnerving sizes of deep sea swells and counting rogue waves, naturally between those the boat is at a low point.