This trip helped me to understand some basic weather phenomenon – the wind at the surface of the earth.
West to East along 31-37 degree in Latitude
In this article, I asked meteorology question: how come bay area is so warm when its latitude is as high as 37 °, it is warmer in the winter than Shanghai, which is just a little bit north of 31°? As my readers pointed it out, it is because the wind.
At that latitude, wind mainly blows from the west to east. Shanghai is cold in winters because the wind from the west is from the mainland, and is cold in nature. The wind for the bay area is from above the pacific ocean. The huge water body makes the air stable in temperature – cool in summer, and warm in winter, and makes that area much warmer and comfortable than Shanghai.
Cross Pacific Flight
The wind also solved another puzzle I had: why it takes longer to fly from SFO back to PVG (12 hours), than from PVG to SFO (10 hours)?
This time, with this knowledge, I paid attention to the real time broadcast of speed on board. From west to east, there are always 150 km/h tailing wind, making the airplane ground speed about 1,000 km/h (10,000 km distance divided by 1,000 is about 10 hours). On the return flight, the head wind is 150 km/h, making the ground speed 750 km/hour, thus cost about 12 hours.
This is the Simplified Answer
This is just the simplified answer of complicated meteorology. I researched on Wikipedia on this, and found many articles on this. The actual wind flows are very complicated, and vary greatly by latitude, and time. I just don’t care about other wind, like those in the south sphere. The simplified answer, wind blows from west to east, works at least for this time, and at this latitude.