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  • 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 questionwhy 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 usehigher latitude = colder temperaturesas a rule of thumb and dive

  • deeper to better understand a placeMaps 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 talkinghas 8

  • time zonesbig

  • 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 withinfrigidSiberia

  • 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 sameless-airreason, 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 withgreen

  • 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 summerand 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 treeswhile 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 adoberedesigning low income

  • neighborhoods with emergency cooling towersincreasing the city's tree canopyand orienting new

  • buildings so they shade sidewalks and courtyardsalong 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