Science of humidity, explaining why SG humidity is higher than in other parts of the world.

 In tropical countries like Singapore, known for its consistent heat and moisture, SG humidity is notably high compared to many other parts of the world. Understanding the science behind humidity can help explain why Singapore experiences such high levels, and why it feels so different from places with lower humidity.

What is Humidity?

Humidity refers to the amount of water vapor present in the air. This vapor can be produced by evaporation from bodies of water, such as oceans, lakes, and rivers, as well as by transpiration from plants. Humidity is typically measured in two ways:

Absolute Humidity – the total amount of water vapor in the air, usually expressed in grams per cubic meter.

Relative Humidity – the percentage of water vapor present in the air relative to the maximum amount that the air can hold at a particular temperature.

When the air contains more water vapor than usual, it can feel warmer, heavier, and more uncomfortable. High SG humidity makes Singapore’s weather feel sticky, especially during the hotter months. The perception of humidity is also affected by temperature – the higher the temperature, the more moisture the air can hold.

Why is SG Humidity Higher Than in Other Parts of the World?

The tropical location of Singapore plays a central role in its high levels of humidity. There are several key scientific reasons behind SG humidity being significantly higher than in many other parts of the world.

1. Proximity to the Equator

Singapore is located near the equator, a region where the sun’s rays are most direct throughout the year. This results in high average temperatures, which causes water bodies, such as the ocean, to constantly evaporate. The warm temperatures increase the amount of moisture the air can hold, and because Singapore is surrounded by water (the South China Sea to the east and the Strait of Singapore to the west), this evaporation is constant. As a result, SG humidity remains elevated year-round, with little variation between seasons.

2. Tropical Rainforest Climate

Singapore falls under the tropical rainforest climate classification, meaning it experiences high temperatures and humidity year-round. The region receives abundant rainfall, often in the form of heavy afternoon showers, which increases the amount of moisture in the air. These frequent rain showers contribute to SG humidity, making the atmosphere feel even more humid after rain as the moisture in the air is trapped by the warm surroundings.

Unlike temperate regions with more distinct seasons (winter, spring, summer, and fall), tropical climates like Singapore’s do not experience large fluctuations in temperature or humidity. Instead, the air remains consistently humid and warm, creating the feeling of an almost “permanent summer.”

3. High Oceanic Influence

Being an island nation, Singapore’s SG humidity is also significantly influenced by the surrounding oceans. Oceans act as heat sinks, absorbing heat during the day and releasing it at night, which moderates temperature swings. However, oceans are also sources of moisture through evaporation. The water vapor evaporates into the atmosphere, increasing the moisture content of the air. This is why places near oceans or large bodies of water tend to have higher humidity levels.

The high level of SG humidity is also influenced by wind patterns that blow moist air from the surrounding seas toward the land, further intensifying the humid conditions in the city-state.

4. Convection and Localized Weather Patterns

The local weather patterns in Singapore, which are primarily influenced by convection and air circulation, also contribute to SG humidity. The daily heat cycle causes the warm, moist air from the surrounding oceans to rise and cool, resulting in condensation and cloud formation. These clouds often lead to localized rainfall, which adds moisture to the air, keeping SG humidity levels high.

Singapore’s frequent afternoon thunderstorms, a feature of its tropical climate, further intensify the humidity. After a rainfall, the humidity levels rise even more, as the wet ground and vegetation release moisture back into the atmosphere through a process known as evapotranspiration.

5. Lack of Dry Seasons

Many regions around the world experience distinct dry and wet seasons, but Singapore lacks a traditional dry season. Its year-round rainfall, combined with the high evaporation rates from surrounding seas, means that SG humidity is consistently high. In contrast, places with dry seasons, like desert regions, experience lower humidity during parts of the year. These regions have air that is typically dry and crisp, especially during the hotter months, as there is little to no moisture in the atmosphere.

In Singapore, there is no real reprieve from humidity as you would find in dry climates. Even during what might be considered the “drier” months, the high humidity remains constant due to the region’s tropical conditions and lack of a dry season.

6. Urban Heat Island Effect

Another factor contributing to high SG humidity is the urban heat island (UHI) effect. Urban areas like Singapore, with their concrete buildings and asphalt roads, absorb and retain heat more than rural areas. This artificial warming can enhance evaporation rates, increasing the moisture levels in the air and contributing to the overall humidity. As Singapore is a highly urbanized city-state, the UHI effect significantly adds to the discomfort of high humidity, especially in densely populated areas.

7. Global Warming and Climate Change

While Singapore’s naturally high humidity is due to geographical and climatic factors, global warming has also had an impact on SG humidity in recent years. Rising global temperatures contribute to increased rates of evaporation from bodies of water, which in turn results in more moisture in the atmosphere. As the world warms, it is likely that SG humidity will continue to stay high, potentially making the air feel even more oppressive.

The science behind SG humidity is a combination of geographic, climatic, and meteorological factors that work together to create a consistently humid environment. From the city’s equatorial location, high levels of rainfall, and influence from surrounding oceans, to local weather patterns and the urban heat island effect, Singapore’s humidity remains higher than in many other parts of the world. Understanding the science of humidity can help explain why the air in Singapore feels different compared to more temperate regions, and why staying cool in such a climate often requires more than just a fan – it requires effective air conditioning to combat the heat and humidity.