Urban heat island effect and climate change (A simplified explanation)

Let’s talk about wind for a start. 🌬️

I don’t profess to know all about wind, but maybe I can learn something new while sharing whatever little I know.

Physics teaches us that air flows from a high pressure area to a low pressure area.

That’s how wind is formed.

When a land area is heated up by the sun, parcels of air rise and condense to form clouds in the sky.

The rising air parcels cause the area to become less dense, creating low pressure.

The air from areas of high pressure will flow in as wind.

Air flows from a high pressure area to a low pressure area. (Source: https://courses.lumenlearning.com/geophysical/chapter/atmospheric-movements-and-flow)

Some surfaces heat up faster than other surfaces, hence creating different areas of high and low pressures.

At the beach, the land heats up faster than the sea during the day, hence air flows towards the land as sea breeze.

On land itself, concrete buildings and asphalt roads heat up faster than parks and forests.

What happens when more forests are cut down to make way for cities?

We experience the urban heat island effect. 🌆

More heat. Stronger winds. More turbulence.

Urban heat island effect (Source: https://gosmartbricks.com/urban-heat-island)

Multiply this effect over time and space, and we will get more extreme weather changes, such as more intense and/or prolonged storms, heat waves, droughts, etc in different parts of the world.

In the longer run, we describe the phenomena collectively as “climate change”.

When measured in terms of the average time span of 35 years, climate may be observed as predictable meteorological patterns, which are fairly constant.

Weather is less predictable, as it changes daily, or even hourly.

Of course, in a much longer term, such as thousands or millions of years, climate changes significantly.

That’s how we get ice ages in between long periods of global warming.

But in the Anthropocene that we live in, climate changes faster than ever before, due to unprecedented emissions of carbon from human activities, such as:

🌳 Deforestation to make way for urbanisation
🌳 Burning of fossil fuels for energy, transport, etc

This is where we are.

On a global scale, winds are influenced by the Coriolis effect, which has to do with Earth’s rotation. 🌏

Coriolis effect (a simplified animation) Source: https://gifimage.net/wp-content/uploads/2017/10/coriolis-effect-gif-11.gif)


It causes prevailing winds to rotate clockwise or anti-clockwise, depending on whether they are in the Northern or Southern hemispheres.

That’s how we get monsoons, cyclones, typhoons and hurricanes in different regions of the world, which are being made more extreme by climate change.

These severe weather events may result in natural disasters, such as flash floods, landslides, mudslides, slope failures, etc, which in turn may cause property damage, injuries and/or deaths of people who are affected.

Sumatra squall in Singapore, caused by the southwest monsoon.

Note: This post is meant to provide only a simplified explanation of climate change. Besides wind, temperature and rain, other weather elements, such as humidity and cloud cover, have a part to play in climate too. Local weather cycles affect global weather cycles, and vice versa. To make things more complicated, deep ocean currents also affect the climate on continents.
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