Sweet baby jesus and the orphans it's got nothing to do with science just scientific convention.
Nobody bats an eyelid when you measure your Sugar in Kg but your butter in lbs.
People still give their weight in Stone despite never being taught in it since about 1989..nobody knows what the fuck a stone is except to have a vague idea that above 12 stone is a big unit and under 8 Stone you may be dying.
Our swimming pools are metres. Road signs are km but timber still inches. Free kicks are yards mostly some fuckin reason. if you gsve your height in m people think your Belgian.
We use Degress C but consider the yanks backwards for sticking to F. Don't get me started on the Brits
Celtic spring is approximate time from the solstice to the equinox so measuing daylight. Meteorological Spring measures min/max temperatures across the months and divides the year in 4 accordingly.
They are just different ways to measure the same thing.