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.