In weather news reports, presenters often mention the “Northeast Monsoon” bringing a cold air mass down to our country… So, what does the term “Northeast Monsoon” mean?
Understanding the Northeast Monsoon
First, it is essential to understand the term “Monsoon.” The English term for monsoon is Monsoon, which originates from the Arabic term “Mawsim” (meaning “season”).
Livescience defines monsoon as a seasonal wind (at certain times) in a region. According to the National Oceanic and Atmospheric Administration (NOAA), monsoons arise from the temperature difference between land and the adjacent ocean. There are two types of monsoons, including: winter monsoon and summer monsoon.
The summer monsoon blows from the Indian Ocean and the Pacific Ocean to the mainland, causing rain and cooler air; meanwhile, the winter monsoon blows from the Asian landmass to the sea, bringing cold air that can lead to rain and cold temperatures.
Why is it called the “Northeast Monsoon”
Different names: The Northeast Monsoon is referred to by meteorologists with various names such as: winter monsoon, northeast wind.
Geographical scope of the Northeast Monsoon (specifically in Vietnam): It affects the Northern and North Central regions of our country.
Additionally, it is also known as “Chướng Wind.” This is the local term used by farmers in the South for the Northeast Monsoon and trade winds.
Origins of the Northeast Monsoon and its name
Monsoon is a seasonal wind (at certain times) in a region.
Professor Dr. Nguyễn Lân Dũng explains that in winter, the temperature over the sea is higher than the temperature on land, and air always moves from cold air regions to hot air regions.
Therefore, the winter monsoon originates from the Siberian high-pressure center, blowing down into our country from the Northeast direction, hence called the Northeast Monsoon.
Simply put, in winter, the Northern region is affected by cold northern air blowing from the northeast, commonly referred to as the Northeast Monsoon.
- Characteristics of the Northeast Monsoon: The Northeast Monsoon carries cold air that comes in waves. Each cold air wave lasts from 3 to 7 days.
- Duration of the Northeast Monsoon: It lasts from November to April of the following year, with a dry cold nature (from November to January of the following year) – and a humid cold (from February to March).
- Consequences of the Northeast Monsoon: The Northeast Monsoon is considered one of the dangerous weather phenomena. It not only causes rain, strong winds, and cold, but also directly impacts human health. During the peak winter months, harsh cold can severely affect crops and livestock.
To add more about monsoons, the Southwest Monsoon is an air mass blowing from the sea to the mainland. The wind originates from the high pressure in the South Indian Ocean. This wind is hot and humid, often leading to rain. The Southwest Monsoon operates from May to October each year.
What types of cold air forecasts are there?
According to the National Center for Hydro-Meteorological Forecasting, depending on the specific situation of each cold air wave, with or without a cold front, cold air forecasts are issued with the following titles:
Northeast Monsoon Advisory Issued When
Cold air is likely to penetrate into our country, fundamentally altering the existing wind system into a northward deviation, causing strong winds of level 6 or higher lasting more than 3 hours over the Gulf of Tonkin (and offshore Central Vietnam);
Or when cold air can penetrate into the Northern region of our country, fundamentally changing the existing wind system into a northward deviation (not considering wind speed), while causing a marked change in weather in a region: becoming overcast, sudden increases in rainfall, and average daily temperatures dropping by 3 – 5 degrees or more at over half of the stations in at least one area;
Or fundamentally changing the existing wind system into a northward deviation (not considering wind speed), while causing widespread rain and thunderstorms in a region, with the possibility of strong wind gusts above level 6 or tornadoes, hail… and maximum temperatures dropping by 5 – 7 degrees or more at over half of the stations in at least one area.
The Northeast Monsoon advisory is issued when cold air is likely to penetrate into our Northern region, fundamentally changing the existing wind system.
Northeast Monsoon and Cold Weather Advisory
This is issued similarly to the Northeast Monsoon advisory mentioned above, but if it is noticed that the cold air wave may cause the average daily temperature in the northern midland and delta regions to drop below 15 degrees (harsh cold and severe cold) and is likely to last for 2 days or more.
Cold Air Strengthening Advisory
This advisory is issued in cases where there is a strengthening of cold air entering our country. While the northern provinces are experiencing cold air, the wind direction has not changed (still a northward deviation), but the wind speed has weakened considerably, offshore winds have dropped below level 5, while there is a possibility of another cold air wave causing strong winds of level 6 or higher lasting more than 6 hours over the Gulf of Tonkin (and offshore Central Vietnam).
Strengthening Cold Air and Cold Weather Advisory
This advisory is issued in cases of strengthening cold air that may cause average daily temperatures in the northern midland and delta regions to drop below 15 degrees and is likely to last for 2 days or more.
