Re: Round trip Flight times vary !!!

Greetings:

Your question also relates to transcontinental travel here in the USA. Flying from
the east coast to the west coast usually takes about an hour longer than flying in
the other direction. Winds at altitude and the earth's rotation both play a part.
in the answer to your question.

The global air mass rotates with the earth just as the ocean waters rotate with the earth.
However, there are rotational effects. The circulation of air in the atmosphere
is activated by convection, the transference of heat
resulting from the fact that warm gases and fluids rise while
cold gases and fluids sink. The large scale global circulation of air takes place
through convection. Warm air rises at the equator and then flows north and south,
while corresponding flows of low altitude cold air move from the poles toward
the equator. Each hemisphere has three belts of convection cells and the
circulation within each belt is greater than the convection between the belts.

If the earth did not rotate, the winds would blow very largely in a north/south
direction. However, the earth’s rotation causes them to veer off course. In the northern
hemisphere this causes the high altitude north flowing winds to veer north east
while the lower south flowing winds veer south west. In the southern hemisphere
the south flowing winds at high altitude veer south west while the low altitude
north flowing winds veer northwest.

When you are flying at high altitude in the northern hemisphere the prevailing
winds are to the east and can easily exceed 160 km/hr (100 miles/hour). Thus
flying east you are traveling with tail winds that increase your ground speed..
Traveling west you are bucking head winds which decrease your ground speed.

The greater distance that you travel, the more the head winds or tail winds will
change your time of flight. Commercial aircraft will fly as much as 500 miles off a
straight line course and will change altitude to catch the fastest of these eastward
winds, the jet stream. Going westward they will reduce altitude to
minimize the headwinds going. However, on the average, in the
northern hemisphere, travel time flying east is less than travel time flying west.

Best Regards, Your Mad Scientist
Adrian Popa ___