Blog 2: Fronts and Air Masses

Lima's weather is affected by a few different fronts that affect its day to day weather. The major air mass that comes into Peru is mP air mass a driven from the south by the prevailing wind currents.It can also get some mE air mass driven by the SE trade winds, thou this is rare. Depending on the time of year and how far the air mass travels north, the temperature can vary from mild to cold.

Major air masses of the world, Source:

http://africanpaintingsgallery.com/air-mass-pictures

The  Major means of transportation for air masses are prevailing wind patterns and currents aloft which drive the movement. For Lima, the sub tropical high pressure system that sits on the Pacific south of Peru, creates northerly winds as it rotates counterclockwise bringing with the the maritime polar air mass. This brings with it a cold front that cools the temperature as it moves inland.

Major Wind Current patterns In January and July  Source:http://www.seafriends.org.nz/oceano/currents.htm

Something that is Happens in Lima, that is unique due to its land scape is the creation of the clouds from the moist and cold air mass as it rises in altitude due to the Andes. Lima it self gets minimal precipitation because as discussed in the previous blog, the temperature through out the year stays pretty mild. As the air mass climbs in altitude and gets colder, it reaches it due point and creates precipitation on the windward side of the Andes.

Clouds create as air mass reaches the Andes, Source: 
http://www.wunderground.com/wundermap