Passage: Singapore has a tropical rainforest climate (Köppen: Af) with no distinctive seasons, uniform temperature and pressure, high humidity, and abundant rainfall. Since this tropical rainforest climate is more subject to the Intertropical Convergence Zone than the trade winds and cyclones are very rare, it is equatorial. Temperatures usually range from 25 to 35 °C (77 to 95 °F). While temperature does not vary greatly throughout the year, there is a wetter monsoon season from November to January.From July to October, there is often haze caused by bush fires in neighbouring Indonesia, usually from the island of Sumatra. Although Singapore does not observe daylight saving time (DST), it follows the GMT+8 time zone, one hour ahead of the typical zone for its geographical location. This has caused the sun to rise and set particularly late during January and February periods, where the sun rises at 7:20 am and sets around 7:25 pm. During July, the sun sets at around 7:15 pm, similar to other cities at much higher latitudes such as Taipei and Tokyo. The earliest the sun sets and rises is in October and November when the sun rises at 6:45 am and sets at 6:50 pm. Singapore remains highly vulnerable to the risk of climate change especially with regards to the rising sea level.

Question: what can cause haze in the tropical rain forest?
bush fires in neighbouring Indonesia