The Tibetan High is a vast high-altitude anticyclone, a huge clockwise swirl of air in the upper troposphere, that builds over the heated Tibetan Plateau each summer and helps pull in, steer and sustain India’s southwest monsoon. It also anchors the tropical easterly jet, a fast river of air high above peninsular India, and its position and strength are closely watched by monsoon scientists.
Because it floats about 12 to 16 kilometres above the ground, the Tibetan High never shows up on an ordinary weather map or a news bulletin, yet it is one of the largest circulation systems of the northern summer. Last updated: 2 November 2026. This explainer covers what the Tibetan High is, why a plateau can create it, how it connects to monsoon onset and the tropical easterly jet, and why it matters for India.
| Attribute | Detail |
|---|---|
| What it is | An upper-tropospheric anticyclone, also called the South Asian High or the Asian Summer Monsoon Anticyclone |
| Typical altitude | Strongest at roughly 100 to 200 hPa, about 12 to 16 km above sea level |
| Typical location | Over the Tibetan Plateau and neighbouring parts of the Himalaya, Iran and south Asia, near 25 to 35 degrees north |
| Season | Builds from late spring and peaks in July and August; fades by autumn |
| Cause | Strong heating of the high Tibetan Plateau, with latent heat from monsoon rain adding to it |
| Wind pattern | Clockwise circulation, with westerlies to its north and easterlies to its south |
| Linked jets | Tropical easterly jet to the south, subtropical westerly jet to the north |
| Link to India | Helps with monsoon onset, upper-level outflow and the stability of monsoon rain |
Key Takeaways
- The Tibetan High is an upper-level anticyclone over the Tibetan Plateau and surrounding areas, strongest in July and August at heights of roughly 12 to 16 kilometres.
- It exists because the high plateau acts as an elevated heat source in spring and summer, warming the air column above it.
- Its southern flank holds the tropical easterly jet, which blows from east to west above peninsular India during the monsoon.
- The shift of the high-level circulation northward onto the plateau is tied to the onset and advance of the monsoon.
- The high is not fixed; it swings between the Tibetan and Iranian regions and these shifts are linked to rainfall patterns across Asia.
- Scientists treat the Tibetan High as part of a coupled system with the Mascarene High, the monsoon trough and sea-surface temperatures, not as a lone driver.
What is the Tibetan High?
The Tibetan High is a large, persistent upper-level high-pressure system, or anticyclone, that appears over the Tibetan Plateau and neighbouring regions during the northern summer, and in the research literature it is often called the South Asian High. In an anticyclone in the northern hemisphere, air circulates clockwise, and in this case the swirl spans thousands of kilometres.
It is different from the high-pressure cells that bring dry, clear weather at ground level. The Tibetan High lives in the upper troposphere, close to the base of the stratosphere, where the air is thin and cold. Meteorologists see it on charts of winds and geopotential height at pressure levels such as 200 hPa and 100 hPa, rather than on the sea-level pressure maps used for weather bulletins.
Seen from the surface, the air beneath the Tibetan High is heated and rising, which is the opposite of a surface high. This distinction matters, because the Tibetan High is a product of rising, heated air that spreads outward at altitude, while a classic surface high is a region of sinking air.
Why does the Tibetan Plateau create a high-pressure system?
The Tibetan Plateau creates a high-pressure system in the upper atmosphere because its surface sits at an average height of about 4,500 metres, so the sun heats a layer of air that is already far above sea level. That heated air column expands and rises, and at high altitude it spreads out, forming an anticyclone.
The plateau covers roughly 2.5 million square kilometres, an area comparable to a large country, and it intercepts strong sunlight because the air above it is thin and clear. In spring, the dry ground heats the air mainly by direct contact, known as sensible heating. As the monsoon arrives, rainfall releases additional heat through condensation, known as latent heating, which reinforces the system.
This idea is sometimes described as the plateau acting as an elevated heat pump or heat source. Early work by scientists such as Flohn in the mid twentieth century argued that heating over the plateau helps reverse the north-south temperature difference in the upper air, an essential step for the monsoon. Later research refined this picture, showing that the Himalaya and the plateau act together, but the broad notion that high-level heating over Tibet matters has held up.
How is the Tibetan High linked to monsoon onset?
The Tibetan High is linked to monsoon onset because the upper-level circulation over Asia reorganises in late spring and early summer, with the high shifting onto the plateau and the westerly jet moving north of the Himalaya. This reorganisation accompanies the arrival of the monsoon over Kerala and its advance across India.
Before the monsoon, in winter and spring, the subtropical westerly jet blows to the south of the Himalaya and the Tibetan Plateau, and the upper air is dominated by westerlies. As the sun moves north, the plateau heats, the temperature contrast in the upper air reverses, and the westerly jet jumps to the north of the plateau around late May and June. At the same time, the upper-level anticyclone, which sits over the Indochina peninsula and the western Pacific in May, builds over the plateau and moves westward.
These upper-level changes occur in step with the lower-level changes that bring the monsoon, such as strengthening south-westerlies and the northward move of the monsoon trough. Forecasters therefore watch the upper-level charts as well as the surface flow when judging whether the monsoon is ready to advance.
What is the tropical easterly jet and how does the Tibetan High drive it?
The tropical easterly jet is a narrow band of strong easterly winds that blows from east to west at roughly 100 to 150 hPa, around 14 to 16 kilometres up, over the Indian region during the monsoon, and it forms along the southern flank of the Tibetan High. Where air circulates clockwise around the high, its southern edge flows towards the west, and this is the easterly jet.
The jet is strongest over southern India and the Indian Ocean in July and August, with speeds that can reach well over a hundred kilometres per hour. It originates in the strong temperature contrast between the heated plateau and the cooler equatorial air to its south, and it extends from south-east Asia across India to Africa.
Its relationship to the monsoon is close:
- Upper-level outflow: Air that rises in monsoon thunderstorms must go somewhere, and the jet carries it away aloft.
- Divergence aloft: The pattern favours air spreading apart at height, which supports rising motion and rain below.
- Monsoon strength: In many studies, a stronger easterly jet goes with stronger monsoon rainfall over India, while a weaker jet goes with poorer rain.
- Cyclones and depressions: The vertical wind structure created by the jet, together with low-level westerlies, affects the development of monsoon low-pressure systems.
How does the Tibetan High affect India’s rainfall?
The Tibetan High affects India’s rainfall by organising the upper-level winds above the monsoon, venting rising air, and influencing where the monsoon trough and rain bands set up. Its strength and position are statistically linked to seasonal rainfall, though the connection is a tendency and not a precise rule.
Research shows that the high does not sit still. It tends to oscillate between a Tibetan mode, in which the centre lies over the plateau, and an Iranian mode, in which the centre shifts west towards Iran and the Middle East. These swings, which occur on timescales from weeks to years, are associated with different rainfall patterns across south and east Asia. A strong, well-placed high over the plateau is generally regarded as supportive of the Indian monsoon, while large departures from the usual pattern have been connected with rainfall anomalies.
Scientists also link the high to the active and break cycle of the monsoon. When the monsoon trough shifts towards the Himalayan foothills during a break, the upper-level circulation changes in step, and the east-west movement of the high is part of the fast variations in rainfall seen within a season.
What is the difference between the Tibetan High and the Mascarene High?
The Tibetan High is an upper-level anticyclone over the Tibetan Plateau, while the Mascarene High is a surface-level high-pressure cell in the southern Indian Ocean, and the two form complementary parts of the same monsoon overturning circulation. One drives high-level outflow, while the other supplies the low-level winds that cross the equator.
| Feature | Tibetan High | Mascarene High |
|---|---|---|
| Hemisphere | Northern | Southern |
| Height of the system | Upper troposphere, about 12 to 16 km | Surface and lower atmosphere |
| Driver | Heating of the elevated plateau and monsoon latent heat | Sinking air in the subtropical belt of the southern Indian Ocean |
| Air motion beneath | Rising, heated air | Sinking, dry air |
| Peak season | July and August | June to August (southern winter) |
| Associated flow | Tropical easterly jet and upper-level outflow | South-easterly trades and the Somali Jet |
Air rises over India, flows outward at height around the Tibetan High, travels south, sinks over the southern Indian Ocean around the Mascarene High, and returns near the surface as the winds that become the southwest monsoon.
How does the Tibetan High relate to the westerly jet and the Himalaya?
The Tibetan High relates to the westerly jet and the Himalaya because the subtropical westerly jet is pushed north of the plateau in summer, and the Himalaya act as a barrier that shapes the heating, airflow and moisture around the high. The seasonal northward leap of the jet is a marker of the shift from pre-monsoon to monsoon.
In winter, the subtropical westerly jet splits around the Tibetan Plateau, with one branch passing south of the Himalaya over northern India and carrying the western disturbances that bring winter rain and snow to the northwest. In summer, the jet moves north of the plateau and the Tibetan High takes over the airspace above. The Himalayan wall also blocks cold dry air from the north and helps trap the moist monsoon air to the south, concentrating the heavy rain over the foothills and the Gangetic plain.
The interplay is a reminder that the monsoon is shaped by geography as much as by sea and sun. Without the Himalaya and the plateau, the strength and pattern of the Indian summer rains would look very different.
Does the Tibetan High trap air pollution?
The Tibetan High traps air pollution in the sense that its strong anticyclonic circulation confines air rising from the surface, forming a reservoir in the upper troposphere and lower stratosphere over Asia during the monsoon. Satellite studies have found a layer of aerosols there, sometimes called the Asian Tropopause Aerosol Layer.
Monsoon thunderstorms lift air from the polluted surface of south and east Asia high into the atmosphere, and the anticyclone holds it in a slowly turning pool. Pollutants and chemicals can then be carried upward into the stratosphere. Researchers study this pathway because it influences the chemistry and radiation balance of the upper atmosphere, even though its effects at ground level are small. This is a developing field, and scientists continue to measure how much material is transported and what it does.
Is climate change affecting the Tibetan High?
Climate change may be affecting the Tibetan High, because the Tibetan Plateau is warming faster than the global average and changes in snow, glaciers and soil moisture alter its heating, but scientists are still working out the net effect on the high and on the monsoon. The plateau is often called the Third Pole because of the vast ice and snow it stores.
Several lines of research are relevant. Warming on the plateau, reduced snow cover and glacier retreat change how the surface absorbs and releases heat. A warmer atmosphere also holds more moisture, which can increase latent heating when monsoon rain falls, potentially altering the strength and extent of the upper-level anticyclone. Some studies suggest the high has expanded or strengthened in recent decades, while others find that natural variability dominates.
The conclusion at present is cautious. The Tibetan High is sensitive to the heating of the plateau and to the monsoon itself, so changes in either are expected to affect it, but projections of its future behaviour carry uncertainty.
How do scientists and forecasters monitor the Tibetan High?
Scientists and forecasters monitor the Tibetan High through upper-air charts, radiosonde balloon observations, satellite measurements and computer models that simulate the monsoon. These tools reveal the location of the centre, the strength of the circulation and the speed of the tropical easterly jet.
India Meteorological Department (IMD) observatories release balloons that measure wind, temperature and humidity through the depth of the atmosphere, and satellites add global coverage. The upper-level patterns are checked alongside sea-surface temperatures, the cross-equatorial flow and the position of the monsoon trough. Research programmes, including the Indian Monsoon Mission, use coupled models to understand how the plateau, the jets and the ocean interact. The Tibetan High is rarely cited in public forecasts, but it informs the expert judgement behind outlooks for monsoon onset, advance and breaks.
Bottom Line
The Tibetan High is the high-altitude crown of the monsoon, an anticyclone born from the heating of the roof of the world that shapes upper-level winds, the tropical easterly jet and the way the monsoon organises itself. It does not act alone, but as part of a coupled system with the Mascarene High, the oceans and the Himalaya, and it remains an active area of climate research.
Frequently Asked Questions
What is the Tibetan High in simple words?
The Tibetan High is a huge swirl of high-altitude, clockwise-moving air that forms over the Tibetan Plateau in summer. It is created by the intense heating of the elevated plateau. It helps organise the upper-level winds that support India’s monsoon.
Where is the Tibetan High located?
The Tibetan High is located in the upper atmosphere over the Tibetan Plateau and nearby regions, with its centre typically around 25 to 35 degrees north. It can shift west towards Iran or east towards the Pacific. It is strongest in July and August at heights of roughly 12 to 16 kilometres.
How is the Tibetan High related to the tropical easterly jet?
The tropical easterly jet is the fast easterly wind on the southern side of the Tibetan High, flowing from east to west high above India. As air circulates clockwise around the high, its southern edge blows towards the west. A stronger jet is generally linked with a stronger Indian monsoon.
Does the Tibetan High cause the monsoon?
The Tibetan High does not cause the monsoon on its own, but it is an important part of the system that supports it. The monsoon arises from the contrast between land and ocean, the cross-equatorial winds, and the moisture and heating involved. The high organises upper-level outflow and is tied to monsoon onset and advance.
Is the Tibetan High the same as the South Asian High?
The Tibetan High and the South Asian High are essentially the same feature, with different names used in different contexts. Scientists also call it the Asian Summer Monsoon Anticyclone. The name Tibetan High highlights the plateau as the source of its heating.
Can the Tibetan High be seen on a weather map?
The Tibetan High cannot be seen on an ordinary surface weather map, because it exists high in the atmosphere. Forecasters see it on upper-air charts at pressure levels such as 200 hPa or 100 hPa. It also shows up in satellite and balloon data as a broad clockwise wind pattern.
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