What is continentality? Continentality is the condition of being in the center of a large landmass, which makes summers much hotter and winters much colder than other places.
Anybody who lives in the center of a large landmass will notice that the temperatures in the summer are higher and the temperatures in the winter are lower than ain reas closer to the edge of the landmass. There is no exact size that a landmass needs to be to have this effect, but the area needs to be sufficiently far from the sea. However, out of all the continents, only those in the northern hemisphere experience continentality. Australia and South America don’t. We will look at why later. So, what causes continentality?
Continentality is caused when an area of a landmass is too far away from the sea to experience the temperature moderation that the ocean brings. The ocean is a great regulator of temperature, and areas that are close to the ocean have much milder temperature ranges. This is because water can absorb a lot more heat than other materials, hold it, and then release it much more slowly. If a city, for example, is near to the sea and the summer temperature is rising, a lot of that heat energy will be taken by the sea, keeping the temperature from going very high. Then, in the winter, when the temperature falls, the sea will slowly release the heat it is holding, keeping the temperature around the city by the sea from going too low. This keeps the extreme temperatures away. The currents in the sea also transfer heat around the globe. Without these currents, the equator would be far hotter, and the poles would be much colder. This cooling and warming effect only lasts for a certain distance. If a city is too far from the sea, there will be nothing to absorb and release heat. A large lake can have a similar effect, but it won’t be anywhere near as effective as an ocean.
Why can water absorb so much heat? Water has a very high heat capacity. All materials can absorb heat, of course, but when they do, the heat energy will rapidly raise the temperature of the material. Water’s high heat capacity means it can absorb heat energy without undergoing an increase in temperature. You can see this if you are trying to boil water for a cup of tea. Water takes a long time to boil. Cooking oils have a lower heat capacity than water, so they heat up fairly quickly. Mercury has a very low heat capacity, so it heats up extremely quickly. Uranium has the lowest heat capacity of all materials.
Water’s high heat capacity comes about because of the bonds between the hydrogen atoms and the oxygen atom. Each molecule of water is made of two hydrogen atoms bonded to one oxygen atom. The hydrogen atoms bond at an angle of 105°, making a V-shaped structure. The atoms share electrons, which makes their bond very strong and the size of the oxygen atom compared to the hydrogen atoms creates a positively charged side and a negatively charged side to the water molecule. This makes it very easy for the water molecules to attach to each other, and it means each bond is very strong. The molecules can absorb a lot of energy before the bonds break apart. That is why water needs to be heated to 100℃, which is a higher boiling temperature than a lot of other materials. And the bonds rejoin very easily, releasing the heat back into the atmosphere. This is why we use water to sweat. It can carry a lot of heat energy out of our body. It is also why things like radiators use water to carry heat or to absorb heat. It is also why you get colder much faster in water than you do in air. The water can absorb a lot more of the heat energy from your body.
The heat capacity of soil and rock depends on the exact type of soil and rock, but it is generally about a quarter of that of water. That means soil can’t absorb as much heat as water, and the heat it does absorb, it releases much more quickly. This keeps the summer temperatures in these areas very high, and there is no heat to release to warm up the very low winter temperatures.
So, why don’t Australia and South America experience continentality? Australia doesn’t experience continentality because it is an island, and even the center of it is not as far from water as the center of North America or the center of Eurasia is. This is the same reason in South America. The continent is big, but fairly narrow. No part of it is really far enough from the sea to have extremes of temperature. And this is what I learned today.
Sources
https://en.wikipedia.org/wiki/Continental_climate
https://www.whsv.com/2021/07/02/continentality-what-is-it
https://oceanexplorer.noaa.gov/facts/climate.html
https://www.ces.fau.edu/nasa/module-3/why-does-temperature-vary/land-and-water.php
https://www.apecwater.com/blogs/water-quality/j-7-can-water-absorb-heat-better-than-most-substances
https://en.wikipedia.org/wiki/Table_of_specific_heat_capacities
Photo by RDNE Stock project: https://www.pexels.com/photo/green-plants-on-desert-field-under-blue-sky-7895270/