A surprisingly large number of freak hailstorms
wreak havoc on shopping malls. And that’s not a coincidence.
Welcome to MinuteEarth.
Big malls - and their even bigger parking lots - are basically just giant slabs of concrete
and asphalt that absorb the sun’s energy and radiate that heat back out, which can raise
the temperature at a mega-mall by several degrees. That warm air rises, pushing up the top-most layer
of the clouds, known as the “tropopause.” Meanwhile, the trees and grass that often
border malls create shade and, through evaporative cooling, keep the surface temperature there cool,
so the surrounding tropopause stays low and traps the rising air in a narrow column. As the column
of air gets taller, the moisture in the clouds starts to condense, forming water droplets. At the
same time, the volume of that column increases, creating a low-pressure vacuum effect that pulls
air molecules towards the center, causing wind. In other words, it creates the perfect conditions for
a storm to form. And the hotter the temperature on the ground, the quicker and higher the storm
cloud rises into the frigid air above, increasing the likelihood that the water in it freezes into
ice balls. The result: concentrated, destructive hailstorms focused directly over shopping malls.
It’s not just malls, of course; any big difference in neighboring surface temperatures
can trigger extreme weather. Mega-cities - known as heat islands - get up to 50%
more rain than the tree-lined ‘burbs. And sun-baked farm fields cut into the forest
are more likely to experience thunderstorms and tornadoes than the forests themselves.
Luckily, through simple actions like planting trees in parking lots and sidewalks and farm
fields for shade and evaporative cooling - or even painting some of those areas white
so they don’t soak up as much heat - we can keep surface temperatures more uniform and
limit destructive conditions from forming in the first place. Otherwise, there will be hail to pay.
Trees and grasses aren’t just good at cooling our micro-environments; they can also help keep our
entire globe cool by sucking up planet-warming carbon dioxide. And now, you too can help suck
up carbon dioxide. With a little information about your habits and lifestyle, our sponsor Wren
calculates your current carbon footprint and makes all sorts of suggestions about how to reduce it.
Wren also allows you to offset the carbon that you do release by making a monthly contribution
towards projects like this one, which turns wildfire-burned trees into natural crop
fertilizer. And for each of the first 100 of you who sign up using the link in the description,
Wren will plant 10 extra trees per person. That’s pretty cool. Thanks, Wren!