We have all noticed how ‘burny’ the sun feels on our skin during the summer months. What causes this intensity, and is it really higher than in other places such as Europe or America?

Source: surfnation.com.au

It is the ultra violet (UV) radiation from the sun that causes the sun to feel harsh and our skin to burn. UV radiation is one part of the electromagnetic spectrum that comes from the sun, together with the infra-red spectrum (we feel as warmth) and visible light (the colours we can see). UV radiation is categorised into 3 types, UVA, UVB, and UVC, with UVB causing damage in the DNA in our skin. While our skin is able to repair itself, it cannot repair absolutely everything, and so over the course of our lives, the damage can build up and lead to skin cancer. UV can also damage various materials causing them to degrade (think of a perished tent, or faded house paint).

The UV index is the measure we use to monitor UV radiation. UV is higher in the summer and during the middle of the day when the sun is directly overhead and has less of the Earth’s protective atmosphere to travel through than when it is lower in the sky in the morning and evening. Although higher UV levels often happen at the same time as higher temperatures, they are independent of another. In an Australian summer the UV maximum can measure between 10 and 14 on the UV index, compared to the UK where it commonly reaches a maximum of 6 to 8. It can reach extreme levels in Europe, but generally for a shorter time. Why is this the case?

In 2025, Earth was closest to the Sun (at its perihelion) on January 5. Next year, Earth’s perihelion will fall on January 4. Getty Images – Littlemn (ABC)

It just happens that during Australia’s summer the Earth is closer to the sun than the northern hemisphere is during its summer. Due to the Earth’s tilt and its elliptical (egg-shaped) orbit around the sun, we are actually 5 million kilometres closer. And being closer to the sun means more UV radiation reaches Earth.

There are a few more reasons compounding the impact of this high UV. In Australia, there are more clear, low humidity days and less pollution to filter out the UV. Altitude can also affect the level of UV. In the Andes, on the equator and 6000m up, the UV index can reach the 20s. Even in Armidale, about 1000m above sea level, new residents and visitors comment on the intensity of the sun. Up here, UV levels may be 10%-12% higher than at sea level

In addition, our outdoor lifestyle increases our exposure to the sun, meaning the personal choices we make are important to reduce our risk of skin cancer. Extreme UV can cause sunburn in as little as 11 minutes.

So yes, we are more likely to get sunburnt in Australia due to higher UV radiation. Protect yourself from skin cancer using the Cancer Council’s 5 ways recommendation: Slip, Slop, Slap, Seek and Slide, and remember to check the SunSmart App daily for your local sun protection times – when UV is 3 or above sun protection is needed.

References:

Lab Notes: Why the Australian sun has a real sting to it – ABC listen

Why is UV so high during Australia’s summer? The ozone hole is not to blame – ABC News

Factors that affect UV radiation levels | Cancer Council NSW