Which Weather Is Your Mood Today?

Meteorologists check the sky every single morning, yet most of us go weeks without checking the conditions inside our own heads. I think that is backwards, and I intend to fix it in the next two minutes. Moods, like weather, are real systems: they roll in, they have patterns, and naming them is the first step to dressing for them.

Answer these questions based on today only — not who you usually are, not who you want to be by Friday. Just current conditions. Your personal forecast is waiting at the end, and I promise there is no bad weather here, only honest weather.

Result	Patterns	Share of patterns
Clear Skies and Full Sunshine	3,887	23.72%
Rolling Thunderstorm	3,633	22.17%
Soft Morning Fog	3,824	23.34%
Cozy Light Drizzle	3,887	23.72%
Record-Breaking Heatwave	1,153	7.04%

Naming the clouds was a pharmacist's hobby

Until the early nineteenth century clouds were widely considered too shapeless to classify at all. Luke Howard, a London pharmacist with an amateur's obsession for the sky, disagreed. In an 1802 lecture he proposed a small set of Latin names, among them cirrus for the fibrous high wisps, cumulus for the heaped ones, stratus for flat layers and nimbus for rain-bearing cloud, which could be combined to describe almost anything overhead. The scheme spread fast, delighted Goethe, and still underpins the classification meteorologists use.

Fog is a cloud that never left the ground

Physically there is nothing to separate fog from the cloud an aircraft flies through; only the altitude differs. On clear, still nights the ground radiates its heat away to space, the air just above cools to its dew point, and vapour condenses into droplets. That is radiation fog, and it explains why valleys fill while hilltops stay clear. The other common kind, advection fog, forms when warm moist air slides across a cold surface, which is the standing arrangement off Newfoundland and along stretches of the Californian coast in summer.

What actually happens inside a thunderhead

A thunderstorm is a machine for separating electrical charge. Inside a towering cumulonimbus, soft hail collides with ice crystals in the presence of supercooled water, and those collisions leave the two kinds of particle carrying opposite charges; updraughts and gravity then sort them to different heights. Once the difference grows large enough the air breaks down, and a lightning channel heats in millionths of a second to a temperature several times that of the sun's visible surface. Thunder is simply that superheated air exploding outwards, which is why counting works: sound covers about a kilometre every three seconds.

Why forecasts run out of road

In 1922 Lewis Fry Richardson published an attempt to compute the weather by hand from physical equations. It took him weeks and the answer came out wrong, but the method was sound, and he imagined a hall of thousands of human calculators keeping pace with the real atmosphere. Machines eventually managed exactly that. What they cannot manage is unlimited range. Edward Lorenz showed in the 1960s that minute differences in starting values grow until two simulations of the same atmosphere share nothing. Forecasters now run many slightly varied versions at once and report the spread, which is why a modern forecast speaks in probabilities and goes quiet somewhere past a fortnight.