Why Study Weather?
Weather & Meteorology Fundamentals 🏆
Course 1 · Chapter 1 · Why Study Weather? Scope & Sources
On the evening of 15 October 1987, a British television forecaster is remembered for telling viewers not to worry because there was no hurricane on the way. The next night, a storm of unusual violence crossed southern England and killed people, brought down millions of trees and became known as the Great Storm. The forecaster's words have been quoted ever since as an example of a forecast gone wrong. The truth is more interesting, and it makes a good first lesson: he was in fact answering a question about a hurricane in another part of the world, the storm that hit Britain was not technically a hurricane, and the models of the day had given only a weak warning (check all of this before repeating it). This chapter explains why weather is worth studying, sets out what the course covers, and shows how to tell weather facts from weather folklore.
Weather and Climate
People use the two words loosely, so it helps to fix them early.
Weather
What the atmosphere is doing at a place and time: today's rain, this afternoon's wind, tomorrow's frost. It changes by the hour.
Climate
The pattern of weather over a long period, usually thirty years or more (check the convention): the typical winters, the average rainfall, the range of extremes.
Why it matters
A cold week does not disprove a warming climate, and a hot day does not prove one. Weather is the individual game; climate is the season's record.
The Five Things to Watch
A huge amount of weather can be described with a handful of measurements.
| Variable | What it is | How it is measured |
|---|---|---|
| Temperature | How warm or cold the air is | Thermometer, kept in the shade and ventilated |
| Pressure | The weight of the air above a point | Barometer; reported in millibars or hectopascals |
| Humidity | How much water vapour the air holds | Hygrometer; often given as relative humidity or dew point |
| Wind | Air moving from one place to another | Anemometer for speed, vane for direction |
| Precipitation and cloud | Water falling or hanging in the sky | Rain gauge, observers, satellites and radar |
Much of the course is about how these five variables interact. Warm air rises, which lowers pressure; moist air cools as it rises and forms cloud; pressure differences drive the wind; and the wind carries moisture and heat from place to place.
How Can Weather Be Forecast at All?
The atmosphere is a fluid obeying the laws of physics, and so in principle its future can be calculated from its present. The English scientist Lewis Fry Richardson tried this by hand around the time of the First World War, and his attempt was a failure in practice but a success as an idea (check the date and the details). Electronic computers made the idea practical: the first successful computer weather forecast was produced around 1950 (check). Since then, forecasting has become a global effort in which observations from weather stations, balloons, ships, aircraft and satellites are fed into computer models (Chapter 7).
What the Course Covers
| Chapters | Theme |
|---|---|
| 2–3 | The atmosphere; heat, moisture and clouds |
| 4–5 | Wind and pressure; fronts and depressions |
| 6–7 | Storms and extremes; how forecasts are made |
| 8 | Weather, climate and change |
Record, Folklore and Memory
The Great Storm story shows why this distinction matters. Three kinds of claim need different handling.
Record
Measured values: a pressure reading, a rainfall total, a wind gust, found in observing records and official reports.
Folklore
Sayings such as "red sky at night, shepherd's delight". Some have a basis: in mid-latitudes weather systems usually move from the west, so a red sunset can mean clear air to the west (check). Others are plain wrong, and none is a forecast.
Memory
What people recall of a famous storm or a hard winter. Good for mood, unreliable for dates and figures: the heat of a summer or the depth of a snowfall is nearly always remembered as greater than the records say.
Where to Get Data and Read More
- Your national weather service. The UK Met Office publishes forecasts, charts, warnings and historical records for free. Other countries have equivalents.
- Surface pressure charts. Analysis charts with lines of equal pressure (isobars) and fronts are published daily and are the best practice for the later chapters.
- Satellite and radar images. Many weather services and agencies publish near-real-time images of cloud and rain.
- Climate records. National weather services and international bodies hold long series of temperature and rainfall (check what is available for your area).
- A home record. A cheap thermometer and a rain gauge in the garden, and a notebook, make the course concrete.
Exercises
In three sentences, explain the difference between weather and climate, and give one example of a mistake people make by confusing them.
Sort these into record, folklore or memory: (a) the pressure at a weather station fell by 20 millibars in a day; (b) "red sky at night, shepherd's delight"; (c) your recollection of the hottest day you can remember.
For one week, note each morning and evening the five variables where you can (temperature, pressure, humidity, wind, cloud or rain), using a forecast service or your own instruments, and write two sentences on what changed and what did not.
Quick Reference
- Weather versus climate: what the air is doing now versus the long-term pattern
- Five variables: temperature, pressure, humidity, wind, precipitation and cloud
- Forecasting: physics plus observations plus computer models
- Limits: chaos (Lorenz); detailed forecasts fade after one to two weeks
- Handling sources: separate record, folklore and memory
- First stops: the national weather service, pressure charts, satellite and radar
- Check: the Great Storm details, dates, the figures for forecast limits
Next chapter: The Atmosphere, which covers its layers, its composition and why weather lives in the lowest of them.