GL 107 Earth Systems Science

K. Hannula

Discussion questions for 11/30/07

1.  What direction does wind blow around high pressure systems in the Northern Hemisphere?

Clockwise.  (Winds blow away from high pressure, and curve towards the right.)

 Which direction does it blow around low pressure systems in the Northern Hemisphere?

Counterclockwise.  (Winds blow towards low pressure, and curve towards the right.)

2.  Which is associated with rainy weather, high or low pressure systems?

Low pressure systems.

3.  What causes monsoons?  Why do monsoon-type conditions (the "Arizona monsoon") develop over the southwestern US in late summer?

Monsoons are a seasonal rainy pattern that occurs in the summer in India and adjacent areas.  They occur because, during the Northern Hemisphere summer, the continent of Asia heats more than adjacent oceans, and the hot air rises, creating an area of low air pressure.  The low pressure sucks in moist air from the Indian Ocean.  When the air rises, it cools, condensing water vapor into clouds that produce torrential rains.

In the Southwestern United States, a similar weather pattern called the "Arizona monsoon" develops in July and August.  Hot air over the Sonoran Desert rises, forming a low pressure system.  Moist air from the Pacific Ocean is sucked into the low pressure system, causing heavy rains.