id: 02355932
dt: j
an: 2005e.02484
au: Reade, John B.
ti: On the scientific explanation of parhelia.
so: Math. Gaz. 87, No. 509, 243-249 (2003).
py: 2003
pu: Cambridge University Press, Cambridge; Mathematical Association (MA),
Leicester
la: EN
cc: M50
ut: haloes; optics; refraction; Snell’s law; history of mathematics;
meteorology
ci:
li:
ab: Haloes, unlike rainbows, occur on sunny days when there is plenty of cirrus
cloud, but no rain. The red band is on the inside and the arc is
centred round the sun, in contrast to rainbows. The theory of haloes
and parahelia was initiated by Mariotte in the 17th century and
completed two hundred years later by Bravais, but neither used
calculus. This article gives the mathematical arguments regarding this
work. Mention is made of Snell’s law and its application in 3
dimensions, as well as of orthogonal and oblique incidence.
rv: