The wave structure of the polar front and the associated upper-tropospheric jet stream is caused by a. surface temperature contrasts between oceans and continents.
b. large-scale mountain ranges.
c. transient weather disturbances (mid-latitude low pressure systems).
d. (all of the above)

Distance that the transcontinental railroad covered from omaha to san francisco.

What is the general rule about surface currents? cold water flows along the ocean floor towards the equator. the east coasts of continents have cold surface currents, and the west coasts of continents have warm surface currents. seasonal and constant offshore winds create significant upwelling along the west coasts of south and north america and africa. the west coasts of continents have cold surface currents, and the east coasts of continents have warm surface currents.

How has the geography of india made it difficult for its people to expand before modern technology?