Context
- The India Meteorological Department (IMD) has issued an Orange Alert for 8 districts of Kerala due to the combined impact of a Low-Pressure Area (LPA) over the Bay of Bengal and a cyclonic circulation over the northeast Bay of Bengal and adjoining West Bengal coast, leading to widespread heavy rainfall.
What is an Orange Alert?
- Orange Alert means “Be Prepared”.
- It indicates the likelihood of heavy to very heavy rainfall (or severe weather) that may disrupt normal life.
- People and authorities are advised to remain prepared for possible flooding, landslides, and transport disruptions.
IMD Colour-Coded Weather Warning System
| Alert | Meaning | Significance |
| Green | No warning | Normal weather conditions |
| Yellow | Be Updated | Heavy rainfall/weather is possible; stay informed |
| Orange | Be Prepared | Heavy to very heavy rainfall likely; take precautionary measures |
| Red | Take Action | Extremely heavy rainfall or severe weather; immediate response required |
Meteorological Systems Responsible
Low-Pressure Area (LPA)
- A region where atmospheric pressure is lower than surrounding areas.
- Causes air convergence, cloud formation, and rainfall.
- Can intensify into a Depression, Deep Depression, and eventually a Cyclonic Storm if conditions remain favourable.
Cyclonic Circulation
- A rotating air circulation around a low-pressure centre.
- In the Northern Hemisphere, winds rotate anticlockwise.
- Enhances moisture transport and intensifies rainfall over nearby regions.
Why Does Kerala Receive Heavy Rainfall?
- Southwest Monsoon brings moisture-laden winds from the Arabian Sea.
- The Western Ghats act as an orographic barrier, forcing moist air to rise and produce heavy rainfall.
- Presence of Low-Pressure Areas, cyclonic circulations, and offshore troughs further enhances rainfall intensity.
India Meteorological Department (IMD)
- Established: 1875
- Ministry: Ministry of Earth Sciences
- Headquarters: New Delhi
- Functions:
- Weather forecasting
- Cyclone monitoring and warnings
- Monsoon forecasting
- Seismological observations
- Climate services and disaster early warnings
| Important CTC from this article for UPSC: Yellow Alert IMD Flash Flood |
Q. With reference to the India Meteorological Department (IMD) colour-coded weather warning system, consider the following statements:
1. An Orange Alert signifies that people should "Be Prepared" for potentially hazardous weather.
2. A Low-Pressure Area is associated with rising air and enhanced cloud formation.
3. Cyclonic circulation in the Northern Hemisphere rotates clockwise.
Which of the statements given above is/are correct?
A. 1 and 2 only
B. 2 and 3 only
C. 1 and 3 only
D. 1, 2 and 3
Answer: A
Explanation:
• Statement 1 is correct: Orange Alert means "Be Prepared."
• Statement 2 is correct: Low-pressure areas promote rising air, cloud formation, and rainfall.
• Statement 3 is incorrect: Cyclonic circulation rotates anticlockwise in the Northern Hemisphere.