The app
Petrichor
Weather lore and a sky journal.
Long before apps and satellites, people read the weather in the sky itself. Petrichor gathers that old wisdom into a pocket almanac and pairs it with somewhere to record what you see with your own eyes.
Dozens of traditional sayings are retold in plain words, each with an honest note on whether real meteorology sits behind it or it is simply charming, sorted by whether they speak of clouds, wind, the moon, animals or the turning seasons.
- Lore
- Journal
- Sky signs
It never forecasts and never pretends to. The patterns page reflects only what you yourself wrote.
The journal
Step outside, glance up, log it
Pick the sky state from a set of hand-drawn options, note how the air feels, set the wind on a little compass rose and judge its strength, add a line about what you noticed, and tag any of the old signs you spotted overhead. Entries gather into a timeline and a calendar that fills in quietly as the days pass, so a season of glances becomes a record.
The patterns
A record that starts to speak
Simple charts are drawn from your own logs: how often each kind of sky turns up, which way your winds tend to blow on a drawn rose, which months you watched most, and which sayings you keep noticing come true. A short sky-signs guide rounds it off with gentle things to look for: a shifting wind, a thickening cloud, a halo round the sun.
Choose your labels, pick a dawn or rain backdrop, set an accent, and keep the whole almanac on the device with no account and no ads.
Get Petrichor on Google PlayPackage com.skyveil.petrichor
Working out
Red sky at night, and why it isn't nonsense
Two pieces of ordinary physics sit behind the oldest saying in the book. The first is why a low sun goes red at all: sunlight near the horizon crosses far more atmosphere, and Rayleigh scattering removes short wavelengths roughly as the inverse fourth power, so the blue is stripped out long before the red. The second is that in our latitudes weather arrives from the west, and a sunset lights the underside of cloud that is still hours away.
At one degree of elevation a ray crosses 26 times the air it would overhead, and about 146 times as much red light gets through as blue. Meanwhile a cloud top at six kilometres stands above the horizon of a watcher on the ground until it is some 282 kilometres away, which at a typical 50 km/h is around five and a half hours of warning. That is the whole of the saying: the colour tells you the western air is clear, and the geometry tells you how far ahead "clear" reaches.
What's not here: no sayings, no journal, no charts of your skies. This page does two calculations for one proverb and stops; it has no opinion on swallows, cows or pine cones, and it is not a forecast for tonight. The almanac and the record are the app.
On paper
IronCedar Interactive
- Company
- SHABEER PLUMBING LTD, trading as IronCedar Interactive
- Director
- Shabeer Ziarmal
- Address
- 72 Basildon Avenue, Ilford IG5 0QQ, United Kingdom
Curiosity, not planning. Petrichor collects folklore and your own notes. It measures nothing, predicts nothing and should never decide whether you sail, climb, drive or leave the washing out. For that, use the Met Office forecast and its warnings. Watch the sun only with it behind a roof or a tree when you go looking for a halo, never directly and never through binoculars. Emergencies: 999, or 112.
Spotted a saying we've told wrong, or one from your part of the country we've missed? Send it with where you heard it. Regional lore is the good stuff.