up148 wrote:yeah, the Jet Stream must have been disturbed or ???, because it dipped way down this past few weeks. Any scientific reasoning for this (earth tilt, rotation or ???)?
Within jet streams, the winds blow from west to east, but the band often shifts north and south because jet streams follow the boundaries between hot and cold air.
Since these hot and cold air boundaries are most pronounced in winter, jet streams are the strongest during both the northern and southern hemisphere winters.
The jet stream dips southward in the winter because of the significant temperature difference between the cold polar air and the warm tropical air, creating a stronger pressure gradient that forces the jet stream to curve further south, bringing colder air masses with it; essentially, the greater temperature contrast in winter drives the jet stream to dip further southward than in summer.
The actual appearance of jet streams result from complex interaction between many variables, such as the locations of high and low pressure systems, warm and cold air, and seasonal changes. They meander around the globe, dipping and rising in altitude/latitude, splitting at times and forming eddies, and even disappearing altogether to reappear somewhere else.
I remember one winter in Tucson, Arizona when it was 17 °F two mornings in a row. As I was getting the motorcycle warmed up before heading for work I heard the duck quacking angrily (like Donald Duck sounded when he was angry.) I went into the backyard to see what was wrong. His Kiddie Wading Pool was frozen solid. The duck was stomping the ice with his feet and cursing because he could not break through the ice for his morning swim.
The cold weather was blamed on the Canadian high (atmospheric pressure) pushing the jet stream over Tucson.
And yes, earth tilt and rotation are involved in all the above.
Reference: https://www.noaa.gov/jetstream/global/j ... he%20poles.