"Whether Weather is Climate"

This great question popped up on my whiteboard a few weeks ago: what's the difference between weather and climate? These two words are often jumbled together, or tossed into places they don't belong, so it's not surprising there's some confusion.

Here's a short version for the impatient: weather is short, climate is long.

Here's a long metaphor for the patient: weather is like watching your day-to-day activities. What time did you leave for work? What did you eat for lunch? You picked those shoes? Specifics, not trends.

Climate is watching your habits every day for thirty years, and using statistics to draw broad conclusions. You leave for work within the same 15-minute window. You generally like sandwiches. You have poor taste in footwear. Trends, rather than specifics.

What's fascinating about weather systems is how frenetically chaotic they are: a tiny change in an unexpected corner can build up to alter the course of an entire storm. This is the so-called "butterfly effect" and makes weather prediction so dang difficult. Sure, we know where a thunderstorm is today, but a billion zillion factors can influence its future movement, so it's hard to say where it's going to be tomorrow.

But despite that complexity it's also fantastically regular. Summers are miserably hot. Winters are unbearably cold. The weather may be unpredictable a few days into the future, but the climate moves (relatively) slowly, making predictions (relatively) easier.

Predicting both the weather and climate is a humongous job, requiring heaps of computing power crunching the numbers day-in and day-out, but that's a story for another memo...