Lesson 1/35 min
Weather and climate
Climate basics
- Bangladesh has a tropical monsoon climate; its main feature is the monsoon wind
- The main elements of climate: temperature, wind and humidity
- The distinct season is the rainy season (Borsha); the king of seasons is spring (Basanta)
- Kalbaishakhi comes in the pre-monsoon season (March-May); it is a north-westerly storm (Banglapedia)
- Winter is dry under the north-east monsoon; heavy rain in the rainy season comes with the monsoon wind (books)
- The most serious direct harm of the greenhouse effect: low-lying land may go under water
Weather and climate at a glance (books)
| Item | Fact |
|---|---|
| Weather centres | 4: Dhaka, Patenga, Cox's Bazar and Khepupara (Patuakhali) |
| Weather offices/stations | 35 |
| Meteorological Department (Zubair) | Under the Ministry of Defence; Agargaon, Dhaka |
| Two regional centres (Zubair) | Storm Warning Centre (Dhaka); Meteorological and Geophysical Centre (Chattogram) |
| 4 seismic observation centres (Zubair) | Chattogram, Dhaka, Rangpur, Sylhet |
| Hottest month; coldest month | April; January |
| Hottest district; hottest place | Rajshahi; Lalpur (Natore) |
| Coldest district; coldest place | Sylhet; Lalkhan, Sreemangal (Moulvibazar) |
| Highest rainfall | Lalkhan/Lalakhal in Sylhet |
| Lowest rainfall | Lalpur in Natore |
| Average annual rainfall | 203 cm (Zubair: highest average 388, lowest 154 cm) |
| Average annual temperature | 26 °C (Zubair: 26.70 °C) |
| Rain in the rainy season | about 80% |
| Lowest humidity (Zubair) | in December (36%) |
| Low-rain zone; high-rain zone | sub-tropical near-dry; Sylhet (sub-tropical very wet) |
Watch out: Banglapedia names Lalakhal in Sylhet as the wettest place (about 6,400 mm on average), January as the coldest month, and says the pre-monsoon season brings 10-25% of annual rain and November-February less than 4%. The two books word Lalkhan slightly differently (Khandokar: in Sylhet; Zubair: in Sreemangal). The hottest district/place, 203 cm, 26 degrees and 80% are book figures that could not be matched with a second source, so they are not in the quiz.
Day, night and rotation
| Date/item | What happens |
|---|---|
| 21 June | Longest day, shortest night in the northern hemisphere |
| 22 December | Longest night, shortest day in the northern hemisphere |
| 21 March and 23 September | Day and night are equal everywhere |
| Daily motion | One turn on its axis takes 23 h 56 min 4 s (about 24 hours) |
Weather warning signals (Zubair)
- Signals go up to 11 for sea ports and up to 4 for river ports
- The 4 river-port signals: Alert, Warning, Danger and Great Danger
Check yourself
In which season does Kalbaishakhi occur?
At a glance
- 1
Tropical monsoon climate; 4 weather centres (Dhaka, Patenga, Cox's Bazar, Khepupara); 35 offices/stations.
- 2
Hottest month April, coldest January; Kalbaishakhi comes in the pre-monsoon season.
- 3
Highest rainfall at Lalkhan/Lalakhal in Sylhet; lowest at Lalpur in Natore (books).
- 4
21 June is the longest day in the northern hemisphere; 22 December the longest night; 21 March and 23 September have equal day and night.
- 5
The distinct season is the rainy season, the king of seasons is spring; the worst direct greenhouse harm is flooding of low land.