4 ms·

I'm not so sure about that. I haven't checked the distances, but the claim is that the author has seen a 610m peak from a 150m observation tower, and that it is

I'm not so sure about that. I haven't checked the distances, but the claim is that the author has seen a 610m peak from a 150m observation tower, and that it is 150 mi away. The line of sight radio/radar horizon across the surface of the earth is well known and easy to calculate (1) and for two sources at different heights you can just add them. I get this as being about 94 mi, less than the stated distance. (1): https://en.m.wikipedia.org/wiki/Radar_horizon https://en.m.wikipedia.org/wiki/Radar_horizon

jameshart 5y ago
No, his claim is he can see it from Anglezark, and he gives the viewpoint altitude there as 298m.
redis_mlc 5y ago
HN, stay pedantic.
someguydave 5y ago
atmospheric refraction could greatly extend that distance. See http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/mirage.html#c2 http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/mirage.html... "The crew of a Canadian ship in the Arctic reported the mirage of a sailing ship off in the distance, upside down. The image was so sharp that the crew could make out the ropes in the rigging and could see people moving about on the deck. Two months later, the ships actually met. When the captains compared their ships' logs, they found that at the time of the sighting the two ships had been 80 miles apart!" (Gallant) The suggested explanation for a visible mirage at such a great distance is the observation of light traveling a long distance when a layer of cooler and denser air is sandwiched between two layers of warmer air (a temperature inversion).
- agf 5y ago
  Except the distances here are twice that, and the farther you get apart the more the curvature matters.
  - someguydave 5y ago
    Yes true, but presumably this report is for observers standing less than 10m off the surface, not on tall mountains or towers
chrisweekly 5y ago
this mixing of miles and meters is problematic for me

jameshart 5y ago

No, his claim is he can see it from Anglezark, and he gives the viewpoint altitude there as 298m.

redis_mlc 5y ago

HN, stay pedantic.

someguydave 5y ago

atmospheric refraction could greatly extend that distance. See http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/mirage.html#c2 http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/mirage.html... "The crew of a Canadian ship in the Arctic reported the mirage of a sailing ship off in the distance, upside down. The image was so sharp that the crew could make out the ropes in the rigging and could see people moving about on the deck. Two months later, the ships actually met. When the captains compared their ships' logs, they found that at the time of the sighting the two ships had been 80 miles apart!" (Gallant) The suggested explanation for a visible mirage at such a great distance is the observation of light traveling a long distance when a layer of cooler and denser air is sandwiched between two layers of warmer air (a temperature inversion).

agf 5y ago
Except the distances here are twice that, and the farther you get apart the more the curvature matters.
- someguydave 5y ago
  Yes true, but presumably this report is for observers standing less than 10m off the surface, not on tall mountains or towers

chrisweekly 5y ago

this mixing of miles and meters is problematic for me