Wind

Extreme Wind

What is meant by extreme wind?
UK Wind Conditions
How does a changing climate affect the likelihood of extreme wind speeds?
Impact of extreme winds on property
How many properties by 2050/2080s will be exposed to extreme windspeeds under a high emission scenario?
How can properties reduce the risk of wind damage?

Highlights

Windstorms are the costliest natural peril covered by insurers in the UK, with damages amounting to ~£1 billion annually^2 _.
UK winds are subject to seasonal and annual variability. At a seasonal level, generally speaking, winter sees increased wind speeds and summer decreased wind speeds.⁷
Climate projections indicate a small winter increase in the late 21^st century, with a corresponding decrease in summer¹⁵.

There is a decrease in storm activity to the south and north of the UK, and an increase in activity directly over the UK, this can be attributed to shifts towards the positive phase of NOA¹⁷.
Annual changes in wind intensity are strongly influenced by the North Atlantic Oscillation (NAO)⁸.
Research suggests climate change will result in the positive phase (phase causing faster wind speeds) of NAO becoming more prevalent, and so increased wind speed and storm frequency over the UK.

What is meant by extreme wind?

What causes wind?

What classifies extreme wind speeds?

Wind Gust Definition

Why Does the UK Experience Prevailing South-westerly Winds?

UK Windspeed Variation

What is the North Atlantic Oscillation (NAO)?

Filler Space

How does a changing climate affect the likelihood of extreme wind speeds?

Winter and Summer UK Wind Projections Under a High Emissions Scenarios, RCP8.5.

UK Storm Frequency

What is the effect of climate change for average wind speed?

Fig. 2 Winter and Summer Trends: Wind gust anomaly seasonally in the UK over the 21st century against the baseline of 1980-2000.

Fig 3. UK Storm Frequency: Projected changes in winter storms relative to the 1981-2000 baseline across two model ensembles. Upper panel exhibits GC3.05-PPE during the time-period 2061-2080, while the lower panel illustrates mean change from 10 members of CMIP5-13 for the time-period 2070-2089.

Fig 4. Average Wind Speed: Spatial trend of wind speed anomaly between the baseline of 1981-2000 and indicated time-period under the RCP8.5 emission scenario.

Why do climate models use wind speed anomalies?

Impact of extreme winds on property

Annual Loss

While changes in wind speed are uncertain, and well within the scope of natural variability, there remain areas of vulnerability.
Major winter windstorms are projected to increase in frequency,¹⁵ and with this there is likely to be an increase in damages, with analysis by ABI estimating an increase of 11%, 23% and 25% in average annual loss under warming of 1.5°C, 3.0°C and 4.5°C respectively.¹⁸
In addition to damage from wind, storms bring with them a host of collateral damage with impacts ranging from storm surge on the coast to flooding in the interior (see the relevant sections in this report).
Climate projections indicate that changes are within the scope of natural variability, and so major changes to current observed windspeeds are unlikely.⁸

Low Windspeed Impacts

In summer the reduction is wind speeds is likely to acerbate heat extremes and put further pressure on properties designed to retain heat.¹⁹
In urban centres low wind speeds have been linked to an increased retention of pollution,²⁰ which is hazardous to human health.²¹ Additionally, considering the recent pandemic, low wind speed has also been linked to the spread of airborne diseases such as Covid-19.²²
Low wind speeds have an impact on renewable energy production, with the wind drought in the summer of 2021 resulting in power company SSE producing 32% less power from it renewable assets than expected.²³ Due to the projection of average wind speed reducing by 8-10% in Europe, it is crucial that sustainable and robust energy systems are put in place to combat the reduction in wind power.²⁴

How many properties by 2050/2080s will be exposed to extreme windspeeds under a high emission scenario?

There will be an increase of 36,235 properties at a high exposure of extreme winds under a high emission scenario from present day to the 2070s.

(Statistics derived from Dye & Durham wind modelling, source UKCP18 data).

How can properties reduce the risk of wind damage?

Extreme wind speeds can varying levels of damage. Fast winds speeds can cause slight structural damage (chimney pots and slates removed), to uprooting of trees. During a violent storm flying debris, downed trees and power lines can be observed causing threat to lives, property, and utilities. Extreme winds cannot be preventing but there are simple, low-cost ways to secure your property, minimising damage.

Check Wind Forcast

Check your insurance policy

Stay updated on weather conditions

Maintain your home

Know who to contact

Bibliography

1. ABI Preparing for Storms 2. Anon The rising cost of storm damage 3. Anon Wind 4. NOAA Why Does Wind Blow? 5. Encyclopedia Britannica 6. National Society Coriolis Effect 7. Met Office 8. UKCP18 Land Projections: Science Report 9. NOAA Climate Variability 10. SEA Offshore Energy Strategic Assessment 11. Met Office North Atlantic Oscillation 12. NAO: Climatic Environmental Impact 13. NAO National Academy of Sciences 14. Tropical Origins Science 15. UKCP Model Projections Science Report 16. . UKCP18, 2021 Products 17. NAO Nature Geoscience 18. UK Windstorms and Climate Change 19. Sustainable Cities and Society 20. Journal of Atmospheric Chemistry 21. Atmospheric Environment 22. Atmospheric Pollution Research 23. Europe's exceptionally low winds 24. Renewable and Sustainable Energy Reviews 25. Research Gate NAO

Extreme Wind

Highlights

What is meant by extreme wind?

What causes wind?

What classifies extreme wind speeds?

Wind Gust Definition

Wind gust refers to a brief increase in wind speed and is analogous with windstorms.

Why Does the UK Experience Prevailing South-westerly Winds?

Wind direction is determined by where the wind is blowing from, therefore winds termed south-westerly originate from the southwest, this is the UK most prevailing (dominant) wind direction.

The prevailing south-westerly winds are due to several factors. The tropics receive more solar radiation, raising temperatures and increasing air pressure. The UK, further north, receives less solar radiation, and so is characterised by lower pressure.

The difference in pressure between the two areas establishes a pressure gradient between the tropics to the midlatitudes (i.e., south to north).5

The westerly component of the prevailing south westerlies is due to the spin of the earth, deflecting the wind. This is termed the Coriolis effect.6

UK Windspeed Variation

UK winds are subject to seasonal and annual variability.

At a seasonal level, generally speaking, winter sees increased wind speeds and summer decreased wind speeds. 7

Annual changes in wind intensity are strongly influenced by the North Atlantic Oscillation (NAO).8

The NAO is a fluctuating pressure gradient consisting of an area of low pressure that sits above Iceland (the Icelandic Low), and an area of high pressure around the Azores (the Azores High) found off the west coast of Spain.

When both areas, Sub-polar Iceland and Subtropical Azores, are experiencing stronger than average pressure phases the difference between the two is greatest.

The pressure gradient determines the strength of the wind. If the NAO is said to be in a 'positive phase', it means the pressure difference is large and wind speeds in the UK are high.10

The UK will also experience stronger storms, increased rainfall11, and higher temperatures in the positive phase.9

What is the North Atlantic Oscillation (NAO)?

Filler Space

How does a changing climate affect the likelihood of extreme wind speeds?

Winter and Summer UK Wind Projections Under a High Emissions Scenarios, RCP8.5.

Seasonal Variability in Wind Gust:

The image below (Fig.2)16 illustrates the wind gust anomaly trend under the RCP8.5 emissions scenarios (High Emissions Scenario).

Fig.2 The top panels plot wind gusts in winter, while the bottom panels plots wind gusts in summer.

UK Storm Frequency

What is the effect of climate change for average wind speed?

There is no trend in winter average wind speed, with significant variability in the model ensemble, and a very slight increase in mean anomaly in the latter half of the 21st century. This slight increase is well within the range of interannual variability produced by fluctuation in NOA.

This reduction in windspeed has implications for extreme heat events, pollution, and wind power.

Fig. 2 Winter and Summer Trends: Wind gust anomaly seasonally in the UK over the 21st century against the baseline of 1980-2000.

Fig 3. UK Storm Frequency: Projected changes in winter storms relative to the 1981-2000 baseline across two model ensembles. Upper panel exhibits GC3.05-PPE during the time-period 2061-2080, while the lower panel illustrates mean change from 10 members of CMIP5-13 for the time-period 2070-2089.

Fig 4. Average Wind Speed: Spatial trend of wind speed anomaly between the baseline of 1981-2000 and indicated time-period under the RCP8.5 emission scenario.

Why do climate models use wind speed anomalies?

Impact of extreme winds on property

How can properties reduce the risk of wind damage?

Check Wind Forcast

Check your insurance policy

Stay updated on weather conditions

Maintain your home

Know who to contact

Bibliography

Join Our Free Trial

The difference in pressure between the two areas establishes a pressure gradient between the tropics to the midlatitudes (i.e., south to north).⁵

The westerly component of the prevailing south westerlies is due to the spin of the earth, deflecting the wind. This is termed the Coriolis effect.⁶

At a seasonal level, generally speaking, winter sees increased wind speeds and summer decreased wind speeds. ⁷

Annual changes in wind intensity are strongly influenced by the North Atlantic Oscillation (NAO).⁸

The pressure gradient determines the strength of the wind. If the NAO is said to be in a 'positive phase', it means the pressure difference is large and wind speeds in the UK are high.¹⁰

The UK will also experience stronger storms, increased rainfall¹¹, and higher temperatures in the positive phase.⁹

The image below (Fig.2)¹⁶ illustrates the wind gust anomaly trend under the RCP8.5 emissions scenarios (High Emissions Scenario).

There is no trend in winter average wind speed, with significant variability in the model ensemble, and a very slight increase in mean anomaly in the latter half of the 21^st century. This slight increase is well within the range of interannual variability produced by fluctuation in NOA.