Red sky at night Weather lore

a red sunset means dry weather next day.

(see red sky @ morning)

red sky @ night, sailor s delight.
red sky in morning, sailor s warning.

(in variations, sailor replaced shepherd )

a red sky – in morning or evening, result of high pressure air in atmosphere trapping particles of dust or soot. air molecules scatter shorter blue wavelengths of sunlight, particles of dust, soot , other aerosols scatter longer red wavelength of sunlight in process called rayleigh scattering. @ sunrise , sunset, sun lower in sky causing sunlight travel through more of atmosphere scattering more light. effect further enhanced when there @ least high level clouds reflect light ground.

when weather systems predominantly move west east, red sky @ night indicates high pressure air (and better weather) westwards. in morning light eastwards, , red sky indicates high pressure (and better weather) has passed, , area of low pressure following behind.