With high pressure, there is a densification of the atmosphere, and there is more “weight” of atmosphere pushing down on the land, seas, and living things.
Low tides, for instance, can be dramatically lower, exposing more beach.
Animals, and quite a few people are sensitive to pressure changes — and this can affect their behaviour, making some tense and irritable.
Others experience headaches or migraines; blood pressure and blood sugar readings can be affected,
and those with arthritis can feel joint pain.
For the past day or so, New Zealand has been sandwiched between the high to the east and a low just off the West Coast.
A low can have the opposite effect, with high tides being much higher, especially if amplified by waves and wind from an onshore direction.
By midday yesterday the barometer was at 1029 hpa, but started to fall in the afternoon.
Looking at old newspaper records by means of the online resource Papers Past, it seems the all-time high barometric reading was at the end of August 1889.
High pressure readings came from all over the country, but Wellington seems to have been the highest with a reading of 1044 hectopascals, measured as near 30.9 mercury inches at the time.
For Gisborne, experiencing a year of broken weather records, Cyclone Gabrielle brought some of the lowest pressures see in recent years.
The lowest seems to have been measured at Whitianga at 4am on February 14, when the barometer dropped to 968 hpa.
Cyclone Bola in 1988 was another intense weather event with very low pressure, recorded at 980 hpa.
In the days before satellites and powerful computers, sailors and farmers alike used to say, “Keep a close eye on the glass!”, meaning watch the barometer’s needle for any sign of bad weather.
If the glass “fell”, it was time to don the oilskins!
