What is sudden stratospheric warming? 640x480

Summary

Sudden stratospheric warming, a meteorological phenomenon, has been linked to unusually cold and snowy winters in the Northern Hemisphere. This occurs when the polar night jet, a ring of strong westerly winds, weakens and reverses direction due to disturbances from the troposphere. The resulting collapse of cold air leads to rapid warming in the stratosphere, sometimes by 30-40°C in just a few days. While not a definitive indicator, such warming can signal an impending cold snap, with about two out of three events leading to subsequent cold weather conditions.

Takeaways

• 🌡️ Over the last few years, parts of the Northern Hemisphere have experienced unusually cold and snowy winters.
• 🌍 One reason for this is a phenomenon called sudden stratospheric warming.
• 🌀 The troposphere extends from the surface to about 10 kilometers and is where most weather occurs.
• ☁️ Above the troposphere is the stratosphere, which has thinner, drier air and little to no cloud cover.
• 🌌 During the polar night, stratospheric temperatures can fall as low as minus 70 or minus 80 degrees Celsius.
• 💨 Around the cold polar air, there is a ring of strong westerly winds known as the polar night jet.
• 🌊 Disturbances from the troposphere can cause the polar night jet to wobble and weaken.
• ⚡ When the jet weakens significantly, cold stratospheric air collapses downward, compresses, and warms rapidly, resulting in sudden stratospheric warming.
• 📈 This warming can cause stratospheric temperatures to rise by 30 or 40 degrees Celsius in just a few days.
• 🌬️ These reversed winds can sometimes reach the lower atmosphere, weakening the Jetstream and leading to high pressure systems, or blocking highs, that bring cold surface winds from the Arctic.

Q & A

What is sudden stratospheric warming and why does it affect our winters?

Sudden stratospheric warming is a meteorological phenomenon where the temperature in the stratosphere increases rapidly, sometimes by 30 to 40 degrees Celsius within a few days. It can affect our winters because when the polar night jet weakens and reverses due to this warming, it can lead to the cold stratospheric air collapsing and warming rapidly, which may influence the weather patterns at lower levels, potentially causing cold snaps and heavy snowfall.

What is the troposphere and how does it relate to our weather?

The troposphere is the lower level of the Earth's atmosphere, extending from the surface to about 10 kilometers. It is where most of our weather occurs because it contains the majority of the atmosphere's mass and water vapor.

What is the stratosphere and why is it important for sudden stratospheric warming?

The stratosphere is the atmospheric layer above the troposphere, characterized by thin, dry air and the presence of the ozone layer. It is important for sudden stratospheric warming because this is where the polar night jet forms, and where the temperature can drop significantly, setting the stage for rapid warming events.

What causes the polar night jet to wobble and potentially break?

The polar night jet can wobble and potentially break due to disturbances coming up from the troposphere. These disturbances can cause the jet to wave more, and when the waves get big enough, they can break, similar to waves on a beach.

How does the weakening of the polar night jet lead to sudden stratospheric warming?

When the polar night jet weakens and even reverses direction due to the wobbles caused by tropospheric disturbances, it allows the cold stratospheric air to collapse downwards towards the pole. As this air compresses, it warms rapidly, resulting in sudden stratospheric warming.

What is the significance of the graph mentioned in the script?

The graph in the script illustrates the dramatic temperature changes associated with sudden stratospheric warming. The green line represents the average temperature in the stratosphere, while the red line shows the actual temperature measurements, which can spike significantly, indicating the warming event.

How can reversed easterly winds from the stratosphere impact the lower atmosphere?

Reversed easterly winds from the stratosphere can work their way down into the lower atmosphere, weakening the Jetstream that normally pushes weather systems from west to east. This can lead to the formation of blocking highs, which can allow cold surface winds to escape from the Arctic, potentially bringing hard frost and heavy snow.

What is a blocking high and how does it relate to sudden stratospheric warming?

A blocking high is a high-pressure system that can form when the Jetstream is weakened by reversed easterly winds from the stratosphere. It can disrupt the typical west-to-east movement of weather systems, leading to cold surface winds from the Arctic, which may result in cold snaps and heavy snowfall.

Is there a direct correlation between sudden stratospheric warming and cold snaps?

While sudden stratospheric warming can be a useful sign that a cold snap is on the way, it is not a definitive proof. Only about two out of three warming events actually result in a following cold snap.

How can we predict the effects of sudden stratospheric warming on our weather?

We can predict the effects of sudden stratospheric warming on our weather by monitoring the temperature changes in the stratosphere and observing the behavior of the polar night jet. However, it's important to note that not every warming event will lead to a cold snap, so additional meteorological data and models are needed for accurate predictions.

What is the role of the ozone layer in the stratosphere during sudden stratospheric warming?

The ozone layer in the stratosphere plays a crucial role in absorbing ultraviolet radiation from the sun, protecting life on Earth. However, its direct role in sudden stratospheric warming is not explicitly mentioned in the script. The warming is more related to the dynamics of the polar night jet and the temperature changes in the stratosphere.