The Key Concept in Physical Geography

    The most important and interesting concept for me in physical geography is how atmospheric circulation controls the climate of every region, leading to the diverse range of landforms and lifeforms in each biome they have.  Below is an image of the basic pattern of atmospheric circulation on Earth.  Bear in mind that this image does not include the jet streams, which also play a large role in climate, but more-so on the immediate weather. 

    The image helps explain why the tropics are hot and wet, why all the hot deserts are roughly at the same latitude, the circulation of midlatitude cyclones, and the movement of polar air.  What isn't shown is how the Coriolis Effect redirects air, depending on the hemisphere we are looking at.  With this image, we can imagine how air masses move on average through any region.  I appreciated learning how the vertical cells (Hadley, Ferrel, Polar) play just as important a role in climate as horizontal circulation.  

    The image helps shape the idea that the conditions that determine geography on Earth are far more intricate than might appear at first glance.  The symmetry of the Earth system is a beauty to behold.  Perhaps it is paradoxical then that Earth should have such a wide range of soils, biomes, climates, species, etc.  For a geographer though, nothing could be more simple. 

NASA's First Air Pollution Map

 

 

    This is a satellite-derived map of average PM 2.5 levels over a five year time-span, courtesy of NASA.  PM 2.5 is a measure of particulate matter in the air that gives it appearance of being hazy and also adversely effects the health of a population. 

    On this map we can see how pollution levels are generally higher around major cities and areas of denser population.  Northeast China is particularly bad, with northern India not far behind.  Other areas you would expect are central Europe and the eastern U.S., which are relatively low compared to India and China.  Areas I thought would be higher are southern California and central Mexico, two places that are notorious for hazy air.  Japan and Indonesia are also lighter than I expected, since they are densely populated nations with well over 100 million people. 

    Areas I didn't expect PM 2.5 to be rampart are in the northern Sahara, Middle East, and western China.  Anyone who knows geography knows these are arid regions with a lot of sand.  Indeed, it appears that mother nature churns its own PM 2.5 factories where there are large deserts of sand- something I hadn't known before.  Sand from the Sahara is actually extremely hazardous to sub-Saharan Africa, causing high levels of infant mortality rates (Neill). 

    Something that concerns me in the future are increasing PM 2.5 levels globally.  And not just from pollution.  The smoke from forest fires is another generator of PM- a threat that is increasing as global warming continues.  Last year, we had the worst spell of smoky skies from forest fires in my 36 years of living here.  It was so bad that we felt ill and had to buy an air purifier! 

Sources: 

NASA.  2010.  Retrieved from https://www.nasa.gov/topics/earth/features/health-sapping.html 

Neill, Pippa.  2020.  Air Pollution From the Desert is Causing an 18% Increase in Infant Mortality.  Airqualitynews.com.  Retrieved from https://airqualitynews.com/2020/06/30/air-pollution-from-the-desert-is-causing-an-18-increase-in-infant-mortality/