ETH climate researcher Daniela Domeisen has documented how the stratosphere influences extreme weather events. What surprised her was the sheer range of potential impacts. She explains what this means for climate research and long-term weather forecasts.
ETH News: In your new study, you've collated many examples of extreme weather events that are linked to what happens in the stratosphere. But we've always been told that such extreme events are due to global warming. Is that no longer the case?
Daniela Domeisen: No, that's still true. Scientists have known for a long time that the stratosphere—the atmospheric layer between 15 and 50 kilometers above the Earth's surface—also influences surface weather. But very few people have explored how the stratosphere can also cause and influence extreme events. That's what we show in our study.
What are some examples of extreme events linked to the stratosphere?
Extreme cold snaps in the northern hemisphere are the most thoroughly investigated among the discussed weather extremes. These can occur when the polar vortex in the stratosphere suddenly heats up and collapses—as is happening right now. Another example is the series of severe storms that hit England in February 2020, leading to heavy flooding. It was remarkable that the storms all followed the same path. This had a direct connection to what was happening in the stratosphere at the time: Back in February, the polar vortex was unusually strong, which allowed it to stabilize the path of the storms. Typically, storms frequently change paths, but in this case, they kept following the same path. We also found evidence that the stratosphere plays a role in other extremes, for example the extreme forest fires in Australia and mini-hurricanes in the Arctic Ocean.
Did the sheer number of such extreme events surprise you?
Yes. This is what the study brings to light. In the course of our research, we kept finding further indications for links between these erratic weather conditions and the stratosphere.
Why is it almost always areas of the northern hemisphere that are affected? Are such events simply less common in the southern hemisphere?
That's a case of publication bias: there are far more studies of extreme events in the northern than in the southern hemisphere. The forest fires in Australia are a prime example of a southern hemisphere event. The polar vortex over the southern hemisphere collapsed much earlier than usual, which encouraged the ferocious fires. Then there's the fact that more people live in the northern than in the southern hemisphere because the latter has fewer land masses. Currently, we know very little about the extent to which the stratosphere influences the weather in e.g. South America or southern Africa.
How is the stratosphere linked to the troposphere, where our weather occurs?
The main signals sent from the troposphere up to the stratosphere come in the form of large-scale atmospheric waves caused by mountains and by differences in temperature between the land and the ocean. Up in the stratosphere, these waves disrupt the winds and can be strong enough to destroy the polar vortex at a height of around 30 km with typical wind speeds of over 200 km/h. What is less clear is how signals return from the stratosphere to the Earth's surface. After a disruption of the polar vortex we often observe that the temperature in the lower stratosphere increases by several degrees Celsius at a height of 10–15 km. This in turn affects our weather, but we haven't yet got to the bottom of how such an event can determine e.g. a storm's path over England.
Do you know how the stratosphere will develop in future?
No, we don't. Today's climate models project entirely divergent tendencies, ranging from a trend towards a warmer or a cooler stratosphere. But we can estimate that the stratosphere is responsible for around 10 percent of our winter weather. The stratosphere may actually mask climate change in the northern hemisphere in that, without the stratosphere's influence, global warming would perhaps be even more pronounced.
What are your research goals?
One of our goals is to improve long-term weather forecasts that cover several weeks to months. Due to its influence on our weather, the stratosphere is a source of predictability for such forecasts. Although an event in the stratosphere doesn't allow us to predict the weather for a specific day several weeks ahead, it does let us estimate the likelihood of events such as cold snaps and heat waves. If, say, the winds in the stratosphere pick up, it's then more likely that northern Europe will see more storms in the weeks that follow. But at the moment, the polar vortex is particularly weak.
So it will be a while before this kind of data is fed into the long-term forecasts offered by weather apps?
Weather models already simulate the stratosphere, just not well enough. This is one of the reasons why we continue to have unreliable long-range forecasts. We have much more experience in making standard, short-term forecasts that cover several days because we have spent decades verifying and improving them. We currently know far less about making forecasts for longer timescales, which involves understanding interactions on a global scale and not just how what happens over the North Atlantic can impact the weather that we expect. Our research is about understanding these global interactions so we can then use what we learn to improve weather and climate models.
What's the next step towards using stratosphere events to improve weather forecasts?
First, we must improve our understanding of the link between the stratosphere and our weather. We know that when something happens in the stratosphere, we often see an effect at the Earth's surface. But one-third of cases leave no trace—and we don't yet know why. In such cases, it's a question of whether it was the stratospheric event or the link to the surface that was too weak. It is also possible that the weather at the Earth's surface was too chaotic, leaving it with no opportunity to react to the stratospheric event. Then there is the question of how long the lower stratosphere maintains the signal. I think of the lower stratosphere as a signaling layer: If the weather receives the signal, its influence can last for a relatively long time—several weeks, for instance.
What new projects do you have lined up?
I want to more closely investigate the regions where long-term forecasts are challenging to make. These include e.g. Europe and parts of South America. What's more, since certain regions in Africa, Asia and South America are underrepresented in the research done to date, we know very little about them. We've launched projects in Brazil and South Africa to help correct this deficit. We want to find out if we can map processes that the models do not yet contain or that we could better integrate into the models by way of numerical methods or machine learning combined with a better understanding of the processes themselves. We also want to find further extreme events for which we can generate long-term predictability. When it comes to heat waves and cold snaps, we already know a lot about how these relate to the weather and how they affect people. But there are also indications of how the stratosphere and further processes influence other extreme events, such as effects on air quality or instances of heavy rain, which have a profound impact on people's lives.
More information:Daniela I. V. Domeisen et al. Stratospheric drivers of extreme events at the Earth's surface, Communications Earth & Environment (2020). DOI: 10.1038/s43247-020-00060-z
Citation:Extreme weather from the stratosphere (2021, January 11)retrieved 10 March 2023from https://phys.org/news/2021-01-extreme-weather-stratosphere.html
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FAQs
What weather conditions are in the stratosphere? ›
The stratosphere is very dry air and contains little water vapor. Because of this, few clouds are found in this layer and almost all clouds occur in the lower, more humid troposphere. Polar stratospheric clouds (PSCs) are the exception. PSCs appear in the lower stratosphere near the poles in winter.
Does stratosphere affect weather? ›As the cold air from high up in the stratosphere disperses, it can affect the shape of the jet stream as the cold air sinks from the stratosphere into the troposphere. It is this change in the jet stream that causes our weather to change.
Will there be a polar vortex in 2023? ›The location and strength of the Northern Hemisphere stratospheric polar vortex on January 4, 11, 18, and 25, and February 1, 8, and 15, 2023. A disruption caused the vortex to shift southward from the pole toward Europe.
Are there storms in the stratosphere? ›Most thunderstorms occur in the lowest layer of the atmosphere, known as the troposphere. But when there is an intense thunderstorm, air can rise from the storm and infiltrate the layer above, called stratosphere.
What are 3 things that happen in the stratosphere? ›Give three facts about the stratosphere.
Light air is at the top of the stratosphere. Heavy air is at the bottom of the stratosphere. Warm air is at the top of the stratosphere. Cold air is at the bottom of the stratosphere.
The stratosphere is where you'll find the very important ozone layer. The ozone layer helps protect us from ultraviolet radiation (UV) from the sun. In fact, the ozone layer absorbs most of the UV radiation the sun sends to us. Life as we know it wouldn't be possible without this layer of protection.
How does the stratosphere affect climate change? ›Atmospheric ozone has two effects on the temperature balance of the Earth. It absorbs solar ultraviolet radiation, which heats the stratosphere. It also absorbs infrared radiation emitted by the Earth's surface, effectively trapping heat in the troposphere.
How does the stratosphere affect global warming? ›Increased thermal emission from rising stratospheric CO2 levels and scattering of solar radiation from stratospheric volcanic aerosols have a direct impact on surface temperatures, while variations in stratospheric water vapor and ozone can affect tropospheric temperatures.
What happens to temperature as you go higher in the stratosphere *? ›Temperature increases as you gain altitude in the stratosphere and the thermosphere. Temperature decreases as you gain altitude in the troposphere and mesosphere.
How hot will us be in 2050? ›They predict that in three decades, more than 100 million Americans will live in an “extreme heat belt” where at least one day a year, the heat index temperature will exceed 125° Fahrenheit (52° Celsius) — the top level of the National Weather Service's heat index, or the extreme danger level.
How hot will it get in 2030? ›
AUnderstanding Global Warming of 1.5°C*
warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate.
Highs could approach 40 degrees Celsius (around 104 degrees Fahrenheit) for the first time – a prediction that prompted meteorologists there to issue a “red” heat warning for the first time ever. To be clear, this would be truly record-breaking heat.
Does lightning happen in the stratosphere? ›The images of stratospheric lightning illustrate the variety of filamentary and broad vertical discharges in the stratosphere that may accompany a lightning flash. A typical event is imaged as a single or multiple filament extending 30 to 40 km above a thunderstorm that is illuminated by a series of lightning strokes.
Does rain come from the stratosphere? ›The stratosphere contains only 15 % of the total mass of the atmosphere and there is not enough of it to form clouds let alone rain.
Is the stratosphere the coldest? ›The top of the mesosphere is the coldest area of the Earth's atmosphere because temperature may locally decrease to as low as 100 K (-173°C).
How does the stratosphere affect human life? ›After 6 miles up the stratosphere starts. The "good" ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays.
What can survive the stratosphere? ›No known organism can survive high altitudes indefinitely. Scientists estimate that even the fittest microbes probably last no longer than a week in the stratosphere, and around a couple of weeks in the troposphere. Eventually they “get fried by radiation,” says David J.
What happens if the stratosphere cools? ›As cooling increases, development of the ozone layer can be affected because a cold stratosphere is necessary for ozone depletion. So releasing more carbon dioxide may not only increase global warming but may also contribute to the formation of the ozone hole.
What is the stratosphere destroyed by? ›Ozone Depletion. When chlorine and bromine atoms come into contact with ozone in the stratosphere, they destroy ozone molecules. One chlorine atom can destroy over 100,000 ozone molecules before it is removed from the stratosphere. Ozone can be destroyed more quickly than it is naturally created.
Why does it get colder as you go higher in the stratosphere? ›This is due to the absorbtion by ozone of the sun's UV radiation and is in sharp contrast to the lower atmosphere. There it generally gets colder as you go higher due to the expansion of gases as the pressure decreases.
What destroys the ozone layer? ›
Researchers found evidence that linked the depletion of the ozone layer to the presence of chlorofluorocarbons (CFCs) and other halogen-source gases in the stratosphere. Ozone-depleting substances (ODS) are synthetic chemicals, which were used around the world in a wide range of industrial and consumer applications.
Does the stratosphere get colder with altitude? ›Temperature in the stratosphere rises with increasing altitude, because the ozone layer absorbs the greater part of the solar ultraviolet radiation. The ozone layer is an absorbing agent that protects life on Earth.
Which is hotter troposphere or stratosphere? ›Why is Stratosphere warmer than the troposphere? Ozone molecules in the stratosphere absorb high-energy ultraviolet light from the sun and convert it into heat. Due to this reason, unlike the troposphere, the stratosphere gets warmer the higher you go!
Is the stratosphere cold or hot? ›The stratosphere is relatively cold at the bottom and gets hotter the higher you go. The temperature difference between the troposphere and the stratosphere is caused by UV light passing through the ozone layer and triggering exothermic reactions.
How hot will the world be in 100 years? ›Since 1880, average global temperatures have increased by about 1 degrees Celsius (1.7° degrees Fahrenheit). Global temperature is projected to warm by about 1.5 degrees Celsius (2.7° degrees Fahrenheit) by 2050 and 2-4 degrees Celsius (3.6-7.2 degrees Fahrenheit) by 2100.
Will 2023 be hotter than 2022? ›But Nick Dunstone added: “For next year our climate model is indicating an end to the three consecutive years with La Niña state with a return to relative warmer conditions in parts of the tropical Pacific. This shift is likely to lead to global temperature in 2023 being warmer than 2022.”
How hot will it be in 100 years? ›According to the 2017 U.S. Climate Science Special Report, if yearly emissions continue to increase rapidly, as they have since 2000, models project that by the end of this century, global temperature will be at least 5 degrees Fahrenheit warmer than the 1901-1960 average, and possibly as much as 10.2 degrees warmer.
What will happen to Earth in 2040? ›The report warns that, by 2040, global temperatures are expected to rise 1.5 degrees Celsius above pre-industrial levels, meaning that most people alive today will see the dramatic effects of climate change within their lifetime.
How hot will the Earth be in 10000 years? ›In 10,000 years, if we totally let it rip, the planet could ultimately be an astonishing 7 degrees Celsius warmer on average and feature seas 52 meters (170 feet) higher than they are now, the paper suggests.
What will happen to Earth in 2050? ›World population is expected to increase from 7 billion today to over 9 billion in 2050. A growing population is likely to increase pressures on the natural resources that supply energy and food. World GDP is projected to almost quadruple by 2050, despite the recent recession.
How hot will Las Vegas be in 2050? ›
Heat risk in Las Vegas, NV
By 2050, people in Las Vegas are projected to experience an average of about 36 days per year over 109.2ºF. Climate change is increasing the frequency and intensity of heat waves, even in places with cooler average temperatures. See more information on heat risk.
2023 is expected to get even hotter. This is partly because a cooling weather pattern known as La Niña that has been in place for three years will come to an end. It is also due to greenhouse gas emissions pushing up temperatures, according to the UK's Met Office.
How hot will Earth be in 2100? ›Results from a wide range of climate model simulations suggest that our planet's average temperature could be between 2 and 9.7°F (1.1 to 5.4°C) warmer in 2100 than it is today. The main reason for this temperature increase is carbon dioxide and other heat-trapping “greenhouse” gases that human activities produce.
Why do thunderstorms spread out when they reach the stratosphere? ›In the higher layer of atmosphere – the stratosphere – air flow is mainly horizontal. The tropopause behaves like a wall, deflecting the updraft's rising air and causing it to spread outward in a way that molds the upper part of clouds into the distinctive anvil shape.
What objects are in the stratosphere? ›The stratosphere is composed primarily of nitrogen and oxygen. It also consists of a layer known as the ozone layer, a blanket of ozone that absorbs harmful ultraviolet (UV) rays from the sun. Ozone is a chemical compound consisting of three oxygen atoms.
What layer of atmosphere do storms occur? ›Troposphere. Known as the lower atmosphere, almost all weather occurs in this region.
Is there a place on Earth where it always rains? ›For years, two villages have claimed the title as the wettest place on earth. Mawsynram and Cherrapunji are just 10 miles apart, but Mawsynram beats its competitor by a mere 4 inches of rainfall. Although it doesn't rain all day in Meghalaya, it does rain every day, Chapple told weather.com.
Which layer is responsible for rain? ›All the atmospheric phenomena such as rains, wind, clouds, etc. take place in this layer. Troposphere contains roughly 80% of the mass of Earth's atmosphere and it composed of composed of nitrogen (78%) and life giving gas oxygen (21%) with small concentrations of other trace gases.
What is the coldest layer of Earth? ›Located between about 50 and 80 kilometers (31 and 50 miles) above Earth's surface, the mesosphere gets progressively colder with altitude. In fact, the top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 degrees Celsius (minus 120 degrees Fahrenheit).
Is there a place colder than space? ›NASA reported that “at a cosmologically crisp one degree Kelvin,” the Boomerang Nebula takes the title of the coldest place in the known universe. One degree Kelvin translates to minus 458 degrees Fahrenheit or approximately minus 272 degrees Celsius.
What is the hottest layer of the Earth? ›
The Inner Core
It is the centre and the hottest layer of the Earth. The inner core is solid and made up of iron and nickel with temperatures up to 5,500oC. Due to its immense heat energy, the inner core is more like the engine room of the Earth.
During the past decades the atmospheric layer closest to the Earth surface, the troposphere, has warmed, while the layer above it, the stratosphere, has cooled (see Figure 1), and related to these changes, the tropopause height has risen globally (IPCC, 2021).
Is the stratosphere getting colder? ›According to NOAA, temperatures in the stratosphere above the North Pole and Arctic region are rapidly rising due to a sudden stratospheric warming event. This comes after the stratosphere's temperatures in that region reached near-record lows in early January.
What happens in the stratosphere temperature? ›In this region the temperature increases with height. Heat is produced in the process of the formation of Ozone and this heat is responsible for temperature increases from an average -60°F (-51°C) at tropopause to a maximum of about 5°F (-15°C) at the top of the stratosphere.
Why is the stratosphere so hot? ›The absorption of incoming solar ultraviolet (UV) radiation by stratospheric ozone is responsible for the heating up of the stratosphere and hence its dynamical stability.
What is the hottest layer of the atmosphere? ›The thermosphere is often considered the "hot layer" because it contains the warmest temperatures in the atmosphere. Temperature increases with height until the estimated top of the thermosphere at 500 km. Temperatures can reach as high as 2000 K or 1727 ºC in this layer (Wallace and Hobbs 24).
What is the stratosphere facts for kids? ›The stratosphere is the second layer of our atmosphere, above the troposphere. The bottom of the stratosphere moves up and down, the way a wave on the ocean rolls, depending on where on Earth you are and what season it is. It can be as low as about 5 miles off the ground and reaches up to about 31 miles high.
What is the coldest layer of the atmosphere? ›Located between about 50 and 80 kilometers (31 and 50 miles) above Earth's surface, the mesosphere gets progressively colder with altitude. In fact, the top of this layer is the coldest place found within the Earth system, with an average temperature of about minus 85 degrees Celsius (minus 120 degrees Fahrenheit).
What gases are in stratosphere? ›The gas composition of the stratosphere is largely the same as that of the troposphere, being composed of nitrogen (78,08%),oxygen (20,95%), argon (0,93%), carbon dioxide and other trace gases (0,04%).