Monsoon
Monsoon in New Delhi
The monsoon is a season in India. The term monsoon refers to a seasonal pressure system that is associated with dry winters and wet summers. See below 2019 and 2018 images and videos for clarification.
2019 Update--October 3
The rains associated with the monsoon continue to drench Delhi every few days. This is good for the water table but flooding in some areas has been devastating. The following videos show a recent thunderstorm that lasted for more than an hour.
2019
The rains have been a little heavier this year, with longer downpours and lasting several weeks longer than 2017 and 2018. There is always a trade-off with rain in India: flooding vs drought. The land absorbs water poorly, so there is rapid, voluminous, hazardous surface run-off when rains are abundant. Insufficient volume of rain is immediately followed by dry conditions tending to drought through the winter and well before the hot seasons begin. People say that the Monsoon has been bringing less rain than past decades, but I do not have the data at hand at this moment. They say it rains less often and for less time than years ago. They say it used to rain heavily for days at a time, without let up. Now, it's more sporadic. (People's memory of weather is never very accurate, of course, so who knows???)
2018
This is Diane's video of the rain associated with Monsoon season. She is in a taxi, heading to the local market. Click on the arrow to view it.
What is the Monsoon?
The monsoon is a seasonal pressure system in India and other parts of southeastern Asia. As the high pressure system migrates northward, warm, moist air from the Arabian Sea and Indian Ocean is drawn over the continent. Temperatures and humidity rise, and rainfall can be heavy.
The end of the Monsoon is caused by the continental high pressure system migrating southward again, causing offshore air flow. This system draws in warm but dry air from the north, that eventually turns cooler as winter approaches. The winters in India are, thus, cool and dry.
The term monsoon refers to a seasonal pressure system that is associated with dry winters and wet summers. It is not the name of the heavy rains.
The line represents the wandering Intertropical Convergence Zone, where The ITCZ wanders southward in the winter, drawing cool, dry air into India from the vast interior of Asia. In the months we refer to as summer, the ITCZ shifts northward, drawing in warm, moist air from the Arabian Sea, Indian Ocean, and Bay of Bengal. This warm, moist air causes considerable atmospheric instability for a period of time. This seasonal pressure system is called the Monsoon. The rains it brings can be enormous. Much needed, but often causing widespread flooding. Like in other regions of the world, people here talk about recent changes in Monsoon patterns. It has been drier than normal for several years; and this year has been particularly rainy.
I will look up rainfall data to get a sense whether there is any real change in the picture or if people are just talking about the weather with the usual lack of information. That is a pattern, probably, that is perfectly steady.
Map images from Wikipedia.
2017
The monsoon is a season in India. The term monsoon refers to a seasonal pressure system that is associated with dry winters and wet summers. See below 2019 and 2018 images and videos for clarification.
2019 Update--October 3
The rains associated with the monsoon continue to drench Delhi every few days. This is good for the water table but flooding in some areas has been devastating. The following videos show a recent thunderstorm that lasted for more than an hour.
Sudden onset of rain. As I exited our building to walk Holly, raindrops started to fall. The video above is taken about 60 seconds later, after we had crossed the street. All of about 50 feet.
This video shows the frequency of lightning in this thunderstorm. The lightning went on like this for more than 30 minutes. This video is taken from inside our terrace space, screened in against mosquitoes.
In this video, you can hear the heaviness of the rain. It's really coming down.
Oddly, perhaps, there was very little wind. At one point, the wind really kicked up, gusting powerfully and bending the mango tree in the garden. In the few seconds it took me to go in and get the phone-video recorder, the winds died down to what you see here and to practically none within a few more seconds. New Delhi's lack of air movement is part of the reason the air pollution is a problem.
2019
The rains have been a little heavier this year, with longer downpours and lasting several weeks longer than 2017 and 2018. There is always a trade-off with rain in India: flooding vs drought. The land absorbs water poorly, so there is rapid, voluminous, hazardous surface run-off when rains are abundant. Insufficient volume of rain is immediately followed by dry conditions tending to drought through the winter and well before the hot seasons begin. People say that the Monsoon has been bringing less rain than past decades, but I do not have the data at hand at this moment. They say it rains less often and for less time than years ago. They say it used to rain heavily for days at a time, without let up. Now, it's more sporadic. (People's memory of weather is never very accurate, of course, so who knows???)
First Day of School 2019
A long, steady downpour on Sept. 7 floods the F-Crescent park.
An hour later, the streets were already dry. Such is the heat stored up in the ground.
This is Diane's video of the rain associated with Monsoon season. She is in a taxi, heading to the local market. Click on the arrow to view it.
What is the Monsoon?
The monsoon is a seasonal pressure system in India and other parts of southeastern Asia. As the high pressure system migrates northward, warm, moist air from the Arabian Sea and Indian Ocean is drawn over the continent. Temperatures and humidity rise, and rainfall can be heavy.
The end of the Monsoon is caused by the continental high pressure system migrating southward again, causing offshore air flow. This system draws in warm but dry air from the north, that eventually turns cooler as winter approaches. The winters in India are, thus, cool and dry.
The term monsoon refers to a seasonal pressure system that is associated with dry winters and wet summers. It is not the name of the heavy rains.
I will look up rainfall data to get a sense whether there is any real change in the picture or if people are just talking about the weather with the usual lack of information. That is a pattern, probably, that is perfectly steady.
Map images from Wikipedia.
2017
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| Dark clouds of the Monsoon season. |
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| Rainfall begins... |
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| The terrace outside my classroom floods rapidly. |
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| ...and is quickly heavier. |
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| ...and heavier. |
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| Wonderful! |
Technical difficulties with these videos. I'll see if that can be fixed....
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| In other news... This image shows the fog and smoke combined in the Ganges River valley. This is caused by a combination of topographic factors and the burning of residual crop matter in the winter. The human contribution to this problem is ghastly but there are some who are working to change current practices. More and more of India's agricultural regions are going "green" and "clean," earning the presently popular "bio" cache. |
Cool to find out more about monsoon rain and where it comes from!
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