At its simplest, Climate is the long-term pattern of weather in a given area, typically averaged over 30 years. To properly define the climate, meteorologists will record a wide range of statistics related to the weather conditions in the specified area, including (but not limited to!) temperature, rain and snowfall, wind speed and direction, humidity, and atmospheric pressure.
Over the years (30 years is the standard period, as we’ve already mentioned), scientists carefully calculate the average of each of these statistics and compare them year by year. It allows them to build up a picture of what the weather conditions in that place are like, and further research can help to predict changes in the environment or even to work out what an area was like many millions of years ago!
It is especially important in our modern world since, due to the actions of humans, we’re experiencing a great deal of change in climates worldwide, some leading to widespread environmental damage and even devastating natural disasters. By learning more about climate and how it changes over time, we can understand what’s happening to our planet and how we can help it recover.
What causes climate?
Well, a lot of things! Different parts of the world can have dramatically different climates thanks to many factors, all of which work together to create different long-term weather patterns.
Here’s a breakdown of some of the most influential factors:
Latitude
Latitude means how far north or south of the equator a given place is. Because the Earth tilts on its axis, and because the
Earth is spherical. The Sun’s rays strike the Earth at
Different angles. The tropics, the regions closest to the Equator, receive the most heat and light because the sun’s rays strike them almost directly. Because of this, temperatures in the tropics are warm year-round. The temperate zones, which are a little further away, have moderate conditions – typically, they’re quite cold in the winter and quite warm in the summer but never reach the extremes of heat that you would find in the tropics or polar zones. The polar zones, the furthest away from the equator, receive the least heat and light because the sun’s rays strike at a very low angle. As a result, temperatures in polar regions are typically extremely cold all year round.
Elevation
Elevation means the height of a place above sea level. On average, air temperature drops about 6.5ºC for every 1000 m altitude: the higher the elevation, the lower the temperature. It means that in a mountainous region, for example, the climate at the top of the mountains will be much colder than at the base.
Topography
Topography means the physical features present in the landscape – natural ones, such as mountains, lakes, valleys, or forests, and artificial ones, like cities, farms, and roads. For example, climates often differ, sometimes quite dramatically, on either side of a mountain. It is because of the way that air currents move.
As air rises over a mountain, it cools. As it cools, it condenses and releases moisture in the form of rain (or sometimes snow, depending on how cold it is). It is called the windward side.
As the now-dry air flows over the mountain, it descends and warms, typically producing deserts. It is called the leeward side. It is most common in regions with long mountain ranges, where the mountains form a long barrier that causes this process to happen over a large area. The dry area is called a ‘rain shadow’ and can extend hundreds of km downwind of a mountain range.
Water Bodies
Land gains and loses heat much faster than water – even when the land is covered in snow, unless it’s cold, bodies of water won’t typically freeze solid, and the bigger the body of water, the harder it is to freeze it. The temperature of a large body of water can influence the temperature of the air above it – the residual warmth can help to warm the air around it a little. Because of this (and some other, much more fiddly factors we don’t need to touch on today), areas close to large bodies of water, whether that’s the sea or a source of fresh water, such as a large river or lake, tend to have much less variation in temperature than areas that are ‘dryer.’
There are a lot of factors that can cause variations in this. Still, in practice, you can see this all around the world – coastal areas are typically much less prone to intensely hot summers and extremely cold winters than areas further inland – although they usually have more variable day-to-day weather as a trade-off!
Dry air gains and loses heat much faster than humid air, so deserts have large daily temperature ranges – baking hot during the day and freezing at night.
The ocean’s currents also play a part in shaping climate – especially in coastal regions. The currents carry hot and cold air along with them, which can help shape seasonal weather patterns along the path of the current, as warm or cold air influences atmospheric circulation patterns (we’ll be talking about that in more detail next). Ocean currents may be considerably warmer or colder than the normal air temperature for that latitude. It can lead to quite jarring effects if the current’s path changes as the sea and air become either colder or warmer.
Atmospheric Circulation
Solar energy and the earth’s rotation create motion in the planet’s atmosphere called planetary winds. There are three basic wind systems in each hemisphere: Polar Easterlies, Northeast or Southeast Tradewinds, and Prevailing Westerlies. These winds blow air masses with distinct regions of origin (ie. Formed over land or water, formed at certain
Latitudes). Winds move warm air toward the poles and cool air
Toward the equator.
These hot and cold air belts shift seasonally as the earth spins on its axis and different latitudes receive direct sunlight. In the Northern Hemisphere, belts shift northwards in the summer, and
Southwards in the winter, whereas in the Southern Hemisphere, it’s the other way around.
Vegetation
Vegetation influences how much of the sun’s energy is absorbed and how quickly this energy is released, which affects the climate.
Plants need light energy from the sun to produce their food via photosynthesis. During transpiration, plants release the water vapor produced during photosynthesis from their leaves into the air, which makes the air around them more humid. Some plants even release particles that promote the formation of clouds.
Large areas of vegetation – especially forests – often act like large bodies of water – they trap heat, so they have a warming effect on the area around them.
All these different factors will shape the climate in a given location.
What’s the difference between weather and climate?
We’ve already touched on it a little. Still, when you boil it down, weather refers to the short-term conditions of the atmosphere, i.e., the specific weather conditions experienced at one moment. In contrast, climate refers to a place’s average weather patterns and shapes over an extended period. The weather can be pretty variable daily – especially here in the UK! – but the climate is the overall weather pattern in the long term and changes much less frequently.
For example, if you described the weather, you’d say something like, ‘today is sunny and warm.’ But, on the other hand, if you were telling the.’
What different types of climates are there?
According to scientists, there are roughly five main types of climate, although there are subgroups within these 5. They are:
- Tropical. In this hot and humid zone, the average temperatures are greater than 18°C year-round, with more than 59 inches of precipitation each year.
- Arid (Dry). These climate zones are so dry because moisture rapidly evaporates from the air, and there is very little precipitation. Of course, they’re often pretty hot, but this isn’t a requirement.
- Temperate. This zone typically has warm and humid summers with thunderstorms and mild winters.
- Continental. These regions have warm to cool summers and very cold winters. In the winter, this zone can experience snowstorms, strong winds, and very cold temperatures—sometimes below -30°C!
- Polar. In the polar climate zones, it’s extremely cold. Even in summer, the temperatures here never go higher than ten °C!
What’s climate change?
Climate change describes a change in a region’s average conditions — such as temperature and rainfall — over a long period. For example, 20,000 years ago, much of the Northern Hemisphere was covered in ice and glaciers.
Global climate change refers to the average long-term changes over the entire Earth. These include warming temperatures and changes in precipitation, as well as the effects of Earth’s warming, such as:
- Rising sea levels
- Shrinking mountain glaciers
- Ice is melting at a faster rate than usual in Greenland, Antarctica, and the Arctic
- Changes in flower and plant blooming times.
Earth’s climate has constantly been changing — even long before humans came into the picture. However, scientists have observed unusual changes recently. For example, Earth’s average temperature has increased much more quickly than expected over the past 150 years. It is largely due to human activity – around 150-200 years ago, we began using huge amounts of fossil fuels to power the Industrial Revolution. Over centuries, we’ve been cutting down large quantities of Earth’s natural forests to create more farmland and space for building.
Certain gases in Earth’s atmosphere block heat from escaping. It is called the greenhouse effect. These gases keep Earth warm like the glass in a greenhouse keeps plants warm. Unfortunately, burning fossil fuels produces a lot of carbon-based gases that alter our atmosphere – it traps a lot more heat, causing Earth to get hotter and hotter steadily. Deforestation contributes to the problem – plants take in carbon dioxide and convert it into oxygen, which helps to balance the gases in our atmosphere and keep them at the ideal level for life on our planet. Losing huge amounts of forests every year means that we lose that extra source of oxygen and have fewer methods to get rid of the excess carbon dioxide.
We’ve already started to see some jarring effects of climate change in recent years – the planet is getting hotter, the polar ice caps are melting, and natural disasters like hurricanes, floods, and wildfires are becoming more common and more severe. Many species of plants and animals are becoming endangered as their habitats are either directly destroyed by humans or changed beyond what we can handle by what we’re doing to the planet.
However, although this all seems very grim, there’s still hope! Conservation efforts worldwide are trying to protect the natural world, defending the habitats of many species. In addition, there’s been a global push towards stopping using fossil fuels and switching to renewable forms of energy, such as solar power and wind turbines. We can also help do our part as individuals by recycling and limiting our energy usage. Of course, it’s not perfect and will take a lot of work from everyone, but Earth’s our home, and it’s our responsibility to take care of it.
