Understanding Why the East Coast of Australia is Drier Than the West Coast
Which is usually drier, the East or West Coast of Australia? Contrary to common belief, the East Coast has a more arid climate compared to its counterpart. This article delves into the climatic and geographical factors that contribute to these differences, providing you with a comprehensive understanding of the unique weather characteristics of both regions. Additionally, we'll address a personal perspective of living in Perth on the West Coast, further emphasizing the contrast with the East Coast's higher humidity levels and more frequent rainfall.
Overview of the Climate on Both Coasts
Australia is home to diverse climatic conditions, and the East and West Coasts exhibit notably different weather patterns. The East Coast, particularly the New South Wales and Queensland regions, experiences a subtropical and temperate climate, while the West Coast, including Western Australia, typically displays a Mediterranean climate with more stable and drier conditions. This article explores the reasons behind the drier conditions on the East Coast.
Rain Shadow Effect
The Great Dividing Range, a significant mountain range running along the eastern coast of Australia, plays a crucial role in creating a rain shadow effect. As moisture-laden air moves inland from the Pacific Ocean, it rises over these mountains, cools, and loses a significant amount of its moisture in the form of rain. This process, known as condensation and precipitation, results in drier conditions on the eastern side of the range.
Prevailing Winds and Their Impact
The prevailing winds in Australia predominantly come from the east, driven by trade winds. These winds bring moisture from the ocean but as they encounter the Great Dividing Range, they are forced to ascend. As the air rises and cools, it loses much of its moisture, creating drier conditions on the eastern side. By the time these winds descend into the interior, most of their moisture has been lost, further exacerbating the dryness experienced on the East Coast.
The Influence of Ocean Currents
The East Coast is influenced by the warm East Australian Current, which can accelerate evaporation, contributing to the drier climate. In contrast, the West Coast is affected by the cooler West Australian Current. This current tends to lead to more stable and moist conditions along the coast. The difference in water temperature and currents plays a significant role in shaping the climate of each coast.
The Role of Subtropical High Pressure Systems
The eastern parts of Australia are often under the influence of subtropical high-pressure systems, particularly during summer months. These systems tend to bring clear skies and limited rainfall, contributing to the drier conditions on the East Coast. In contrast, the West Coast experiences more frequent and stable precipitation patterns.
Geographical Features and Their Impact
The distribution of land and water bodies also contributes to the different rainfall patterns observed on both coasts. The interior of Australia is largely arid, and the proximity of the East Coast to this arid zone can contribute to lower humidity and precipitation levels. This geographical feature further intensifies the drier climate on the East Coast.
A Personal Perspective from the West Coast
Living in Perth, a city on the West Coast of Australia, it is evident that the climate here is considerably drier compared to the East Coast. Summer humidity levels in Perth can drop to as low as 20%, a phenomenon often considered unseasonably dry. In a climate where a 40% humidity level is typically considered quite moist, the aridity of the West Coast becomes even more apparent.
The stark contrast is highlighted when contrasting it with the situation on the East Coast. During recent years, East Coast regions have faced frequent flooding due to extremely heavy rainfall. However, in Perth, the rainwater supply in my rainwater harvesting system has been nonexistent since January 10th, and my gutters have not run with rainwater since September 2022. This personal experience underscores the climate differences between the two coasts and emphasizes the aridity and scarcity of rainfall on the West Coast.