The angular radius of a water rainbow is 42°.
The angular radius of an ethane radius is 56°.
The angle 2φ, in the Wikipedia article, is the angular radius: the angle between the direction of the sun and the refracted light forming the rainbow.
Don't be fooled by the 2 in 2φ. That is just the way they have defined some things in their construction. They happen to solve for φ, which then needs to be doubled to obtain the angular radius.
Greg Egan /
npub12c…gd38p
2024-09-15 21:28:20
in reply to nevent1q…zk5u
Author Public Key
npub12cuzzqzv8e8y7na77a9zv47mx2v6pec60qs5h7takzmv5p0mw0fsmgd38pPublished at
2024-09-15 21:28:20Event JSON
{
"id": "4345f8dca0fef0fed05e5aaef1ad0b579e62f54fd4b509333103e3260f72de93",
"pubkey": "563821004c3e4e4f4fbef74a2657db3299a0e71a78214bf97db0b6ca05fb73d3",
"created_at": 1726435700,
"kind": 1,
"tags": [
[
"proxy",
"https://mathstodon.xyz/@gregeganSF/113143690059123196",
"web"
],
[
"p",
"563821004c3e4e4f4fbef74a2657db3299a0e71a78214bf97db0b6ca05fb73d3"
],
[
"p",
"9a6a1a8eefd0b53d7e0c966ab35bd904151246f03b1be98fa0d2d0eeb4940320"
],
[
"p",
"d0e3bf5db9c015af00a382d9cbe34b26b89c16d0386cefa4d20f661a7b7d4bf1"
],
[
"p",
"4891132e6ed57d6d14bee25322d4d485a164e3252fbabe441572f93ad8ca1769"
],
[
"e",
"dd80f3c0423d5a6b20e827be414189ec714944ece6343453961f11cecd3b505e",
"",
"root",
"9a6a1a8eefd0b53d7e0c966ab35bd904151246f03b1be98fa0d2d0eeb4940320"
],
[
"e",
"b403b8f022d469a57b9fb485fd834da0656add9264d3a9051715e05d433821df",
"",
"reply",
"9a6a1a8eefd0b53d7e0c966ab35bd904151246f03b1be98fa0d2d0eeb4940320"
],
[
"proxy",
"https://mathstodon.xyz/users/gregeganSF/statuses/113143690059123196",
"activitypub"
],
[
"L",
"pink.momostr"
],
[
"l",
"pink.momostr.activitypub:https://mathstodon.xyz/users/gregeganSF/statuses/113143690059123196",
"pink.momostr"
],
[
"-"
]
],
"content": "The angular radius of a water rainbow is 42°.\n\nThe angular radius of an ethane radius is 56°.\n\nThe angle 2φ, in the Wikipedia article, is the angular radius: the angle between the direction of the sun and the refracted light forming the rainbow.\n\nDon't be fooled by the 2 in 2φ. That is just the way they have defined some things in their construction. They happen to solve for φ, which then needs to be doubled to obtain the angular radius.",
"sig": "2ab2e4b78a68cd07c9da6b3e43ffd20e89e148d4460a73b6b2159ee573761a7f0cadbd710c3dc4351888e7ba1385f44a519c95b4e3f361b0b6a41ff1d48ba698"
}