These days, air temperature is something we
can easily check on our phones or by stepping outside before deciding if we really need
the t-shirt and sweater and puffy jacket and rain slicker and two pairs of socks and a
hat and gloves. [Whew, I’m sweating already!] But air temperatures influence so much more
than what we wear. Global temperature patterns have long affected cultures and community
decision-making and the landscape of plants and animals. Thousands of years of atmospheric observations
and science have led up to all we know about a region’s temperatures and even how we
think about a place. Like, if we know nothing else about the vast
region we’ve long called Siberia, we know that it’s cold. Really cold. But there’s
more to it than that, just like there was more to the cultivation of bananas or the
geo-ecosphere of Iceland. (If you haven’t already noticed, we'll be
doing a lot of these deep-dives to, I dunno, "go bananas" throughout this series.) And today we’ll talk about ice and snow
and regions like Siberia with temperatures that drop well below zero -- but more broadly
how the science and patterns of air temperatures affect geographical space, place, and human
interactions with the Earth. I’m Alizé Carrère and this is Crash Course
Geography. [INTRO] As geographers, one of our fundamental goals
is to answer the question “why is that happening here and not there?” So while we could look
up an exact temperature reading, we’d be focusing on a single data point and missing
the larger connections that tell the story of the Earth. Like, Siberia can claim the lowest temperature
ever recorded where people actually live, but that alone doesn’t tell us why it has
such an enduring fascination as inhospitable, forbidding, and a place of exile. Actually, humans have lived in Siberia for
the last 40,000 years. It’s been home to many nomad groups, is thought to be the birthplace
of the Turkic people, and was part of the Mongol Empire in the 13th century before slowly
coming under Russian control in the 16th century. All these habitats and different peoples have
survived despite and because of Siberia’s temperature. Yeah, it’s really cold. But
we can unpack that simple statement about the Earth's atmosphere and air temperature
by using geography to explore the space, place, and human-environment interactions. In fact, we can get a pretty good idea of
Siberia's story and air temperature patterns with just four questions. First: what is the latitude of the place?
As geographers, we want to see how temperature plays into the larger pattern of global weather
systems, of biogeography, and as we'll see soon, climate zones and the global distribution
of plants and cultural traits. And many air temperature patterns are tied to latitude. In our episode on the movements of the Earth,
we saw how latitude is tied to how much insolation, or incoming solar radiation, each location
receives. During the day, the short waves from the hot
Sun ping-pong through the atmosphere and absorb into the ground, warming the surface. At night
when a place isn’t receiving insolation anymore, the cooler Earth is still radiating
out long-wave energy. So air temperature drops. There’s actually a time lag between our
sunlight and air temperature cycles because the Earth takes a bit to warm up. Which is
why the hottest part of the day usually happens a little after 2pm. And this phenomenon is mimicked on a bigger
scale throughout the year as the Earth revolves and the latitude where the Sun is directly
overhead shifts north and south between the Tropics of Capricorn and Cancer. So, we get
a daily and annual air temperature cycle. We can actually track these cycles and map
the air [-- which is kind of mind-blowing when you think about it. We can't see air
around us but we can map it!] These two isopleth maps, or maps that show
the continuous distribution of data, show the average air temperatures around the world
in January and July using isotherms, or lines joining locations that have the same temperature. In the course of a year, as the latitude where
the Sun is directly overhead shifts, the isotherms follow. Remember, places get less insolation
as we move from the equator to the poles. The isotherms also show how air temperature
varies season to season. At the equator there’s almost no difference between seasons. But
the temperatures at the poles vary a ton. Basically, we can use “higher latitude = colder
temperatures” as a rule of thumb and dive deeper to better understand a place.
Maps like these are one way we can expand on latitude temperature patterns. Even for
a vast geographical region that makes up three-fourths of Russia’s total territory like Siberia.
It’s big. Like, we’re talking “has 8 time zones” big. Siberia spans all the way between 50 degrees
and 70 degrees north latitude, which means it tips over into the Arctic Circle. On our
January map, winter in the Arctic and subarctic brings plunging temperatures. Like, the frigid -50 degree celsius isotherm
cuts across northeastern Siberia. The just-under-1400 people who call the town of Verkhoyansk in
the Arctic Circle home deal with average minimum temperatures as low as -57 degrees celsius.
So yeah, parts of Siberia are indeed, “very cold." The extreme cold of the high latitudes means
that even though there’s lots of land that can be farmed, the short growing season plus
the mud created by melting snow and ice make agriculture difficult. Even building roads
is a problem. So, Siberia remains largely uninhabited except for small scattered lumber
and mining settlements. The second question we can ask is: how far
away is the place from the ocean or sea? On the isotherm maps, the greatest temperature
difference from east to west happens where the isotherms leave large landmasses to cross
the oceans. Let’s follow the 15 degree Celsius isotherm.
It lies over central Florida in January. By July it’s moved farther north where it then
loops into northwestern Canada. But the isotherms over oceans shift much less. Land has a low specific heat, or how much
heat is needed to raise the temperature 1 degree celsius. On the other hand, water has
a high specific heat, so oceans need more heat for temperatures to increase 1 degree. Water can also store heat by moving it down
to mix with deeper, colder waters through convection. So a really important factor for
air temperature is ocean distribution. Places far from oceans tend to have a stronger
temperature contrast from winter to summer. This condition is called the continental effect
or continentality. Siberia has extensive coastline and sits within
the vast interior of the Asian landmass. Which means it has inland areas with great seasonal
temperature fluctuation and areas on the coast where the ocean keeps things more stable. South of the Arctic Circle, Yakutsk's high
latitude and location in the continental interior means its annual temperature jumps from -45
up to 20 degrees Celsius. So it can be far below zero one moment and
you're sipping hot honey tea. But several months later, it's warm enough to drink some
iced kvass (which, according to the power of the internet, is like a refreshing soda
though I’ve never tried it. I still have to visit Siberia, so if you’ve tried it,
tell me what you think!) Both continentality and the ocean influence
Siberia’s climate significantly. Russia’s Far East has a distinctive subregion with
longer growing seasons and a milder climate because it’s close to the Pacific Ocean. As we move southwest, the wetter climate of
East Asia meets the continental climate of the Siberian interior to create a zone of
ecological mixing -- coniferous forests mix with Asian hardwoods, and reindeer mix with
siberian tigers and leopards. There’s actually great landscape and climate diversity within
“frigid” Siberia. Our third temperature-related question is:
what is the elevation of the place? At high elevation, or how high a point is
on Earth’s surface relative to sea level, there’s less air to absorb solar energy,
and we feel a drop in temperature. For the same “less-air” reason, we also
feel a drop in temperature at high altitude, which refers to the height of an object, like
an airplane, above Earth’s surface. Basically, highlands are always colder than lowlands.
Mount Kenya is about 5200 meters high and is located at the equator, yet is still cold
enough to have glaciers. The isotherms around the Rocky Mountains dip
down in both summer and winter. The effect is even more noticeable in the Andes Mountain
in South America. The many mountain ranges in Siberia, like
the Altai Mountains to the south or the Verkhoyansk mountains to the east will be colder than
the surrounding lowlands. They also mark changes in the ecosystems because of the difference in temperature and moisture that mountains provide. Like, in many of these higher elevations and
high latitudes, with cold temperatures comes snow and ice. Which go on to influence temperature
in a feedback loop of sorts. The high albedo, or reflection of insolation,
of the snow keeps winter temperatures low by reflecting much of the winter insolation
back to space. The type of surface can even influence temperature on top of latitude,
continentality, and elevation. This idea brings us to our fourth and final
question: is the place an urban area, or a rural area? Cities across the world are actually trying
to increase their albedo with “green” roofs covered in plants, more trees, and painted
white surfaces. The darker, sealed surfaces of human-made urban environments absorb a
lot of solar energy without also absorbing moisture. So we end up creating urban heat
islands where air temperatures are several degrees higher than in the nearby suburbs
and countryside. But there’s more to solving urban heat islands
than that. Let’s go to the Thought Bubble. In modern-day Phoenix, Arizona we’re actually
smack in the middle of the Sonoran desert, which can get quite hot. A city, aka urban heat island, in the desert?
Even hotter. Despite that, Phoenix is one of the fastest
growing metro areas in the U.S. As the city sprawls into the surrounding desert,
it’s increasing its paved, sealed surfaces, making it the fastest warming city in the
U.S. as well. Temperatures above 37 degrees Celsius are
common in the summer, and like in other parts of the world, heat related deaths are a public
health issue. And as climate change increases heat in the
lower part of the atmosphere, summers are projected to only get hotter and longer. On top of that, the effect of urban heat isn’t
evenly distributed because of land use, like the distribution of highways, parking lots,
and parks. Measuring temperatures across various city
spaces can reveal a 10 degree difference between neighborhoods less than two miles apart. For example, wealthier neighborhoods are usually
well-shaded with trees, while low income neighborhoods are hardest hit by heat, meaning
those communities suffer disproportionately from health threats due to extreme heat. Phoenix has introduced a program that treats
heat readiness on par with climate change disaster preparedness. Plans include a return to traditional building
materials like adobe, redesigning low income neighborhoods with emergency cooling towers, increasing
the city’s tree canopy, and orienting new buildings so they shade sidewalks and courtyards,
along with alerting residents with text notifications when a heat wave is imminent. But city-wide measures can only do so much,
and combating urban heat islands has to do with where and how resources are given to
the communities that need them most. Thanks, Thought Bubble. Studying air temperature
also means we have to ask questions about equity -- how does temperature affect the
people that live in a certain place, and who has access to the public services and facilities
to stay healthy and go about their lives? We saw how latitude, ocean proximity, and
elevation come together to make Siberia so cold that very little grows and few people
live here. In the past, the search for valuable fur and minerals -- which still continues
-- stimulated Russian expansion into the vast wilderness of Siberia. Today, melting sea ice in the Arctic Ocean
from higher temperatures has opened up shipping lanes which will bring increased trade and
growth to the Northern Siberian region. But it also adversely affects indigenous reindeer
herders of the Russian Arctic. Delays in sea ice freezing disrupts seasonal migration routes,
destroying a way of life and economy. The environment creates opportunities and
challenges to which humans respond. But human-environment interaction is a two way street. We’ll keep
examining these issues as we explore larger patterns of global climate and their impact
on lives both human and non-human. Many maps and borders represent modern geopolitical
divisions that have often been decided without the consultation, permission, or recognition
of the land's original inhabitants. Many geographical place names also don't reflect the Indigenous
or Arboriginal peoples languages. So we at Crash Course want to acknowledge these peoples’
traditional and ongoing relationship with that land and all the physical and human geographical
elements of it. We encourage you to learn about the history
of the place you call home through resources like native-land.ca and by engaging with your
local Indigenous and Aboriginal nations through the websites and resources they provide. Thanks for watching this episode of Crash
Course Geography which was made with the help of all these nice people. If you want to help
keep Crash Course free for everyone, forever, you can join our community on Patreon.
