In a nutshell
David Brunt, the father of meteorology, studied fluid dynamics as the weather is actually caused by gases in motion. He worked out which country's atmosphere is the healthiest.
Brunt was brilliant at maths. He soon realised the power of statistics in tackling complicated problems that came with a whole pile of data. It was during his military service in the First World War that he first got mixed up in the practicalities of weather forecasting and the more difficult aspects of meteorology.
After the war he joined the Met Office at a time when they needed increasingly detailed weather forecasting, as aeroplanes were being used more and more often. He studied the meteorology of the lower regions of the atmosphere. This work was kick-started by concerns following the use of poison gas by both sides in the First World War, when each side was guilty of irresponsibility because no one knew how winds would disperse the gas.
Sayings like 'Red sky at night, shepherds delight; Red sky in the morning shepherds' warning' are totally unscientific.
Careful collection of data on temperature, pressure and wind strength is needed before any surmising can be done. Basically, meteorology is the study of fluid dynamics, the weather simply being gases in motion. However, the vast scale of the atmosphere ensures that the study is highly complicated.
This is why the mathematics of statistics, in which David Brunt was such a natural, is so important. Towards the end of his research career he tried to link weather conditions and human health. He concluded that the best conditions of monthly temperature were between 24C and 0C for the hottest and coldest months of the year. Most of north west Europe meets these conditions. He reckoned that the ideal climate for healthy humans is in New Zealand.
It's interesting that two other Welsh scifiles, Sir Graham Sutton FRS and Sir John Houghton FRS, made big contributions to meteorology and both held big jobs in the Met Office. Could it be that the Welsh rain breeds high quality meteorologists?