Why Do Coastal Areas Get More Rain?

Even if you plan your beach holiday around the dry and rainy seasons, there’s always a chance of rain at the coast. Some areas get lots more rain than others. Have you ever wondered why it rains more at the coast? This article explains why coastal areas receive more rainfall than other inland areas. Read on to find out!

On average, coastal regions receive more rainfall than inland regions. It rains more in coastal areas because there is more evaporation from the sea. With more evaporation at the coast, more water is collected in the air, which causes higher rainfall in coastal regions.

The ocean substantially influences Earth’s climate and weather by pouring most of the water out on land. Here we describe why it rains more at the coast than inland and what effect the ocean has on rainfall.

Why Do Coastal Areas Get More Rainfall Than Others?

Several factors influence rainfall on Earth like air temperature, airflow, moisture-bearing winds, humidity, ocean currents, coastal distance from inland, and mountains.

Coastal areas typically get more rainfall than other areas, and the reason for this is that there is high humidity and evaporation over the ocean that leads to higher rainfall. Also, when the wind blows from sea to land, it brings moisture to the nearby coast. 

Because the ocean is a large water body and is nearby, it affects the amount of rainfall the coast gets. The more water evaporates from the ocean, the more clouds are formed that provide more rain.

The Water Cycle = Evaporation – Condensation – Precipitation

Most of Earth’s rain comes from the oceans, and rainwater finds its way back to the oceans, just to be evaporated again to begin the cycle all over. It is called the water cycle. The Earth’s water cycle is complex.

The water cycle happens when water travels from Earth’s surface into the air to return to Earth again. This process occurs in three phases.

The water warmed by the sun evaporates from lakes and oceans. When the water vapor rises into the air and cools, it turns into droplets of liquid water to form clouds, and when the water droplets in the clouds get heavy, they fall back to Earth as rain. The rainfall flows into streams and rivers and eventually goes back to the oceans. 

It takes a water molecule to evaporate and rain back on Earth around nine days. Plant life on Earth also breathes out water vapor that gets released in the air to contribute to rainfall.

Water Cycle Explained

  • Evaporation – happens when the sun heats water in the ocean, rivers, lakes, or land and turns it into invisible gas called water vapor in the air.
  • Condensation – happens when the water vapor rises into the air, and when the air cools down, it changes into drops of water, forming clouds.
  • Precipitation – happens when the clouds get heavy when more and more water droplets condense to join into more significant, heavier drops, after which water begins to fall back to Earth as rain. Precipitation also includes snow, sleet, and hail.
  • The cycle starts over when rainwater finds its way back to the ocean to start everything all over again.

How Do the Oceans Affect Earth’s Weather?

The oceans are continuously evaporating, increasing the humidity and temperature of the surrounding air to form rain that is moved over land by winds. Large water bodies like the ocean, lakes, and rivers can affect Earth’s climate and rainfall.

The Oceans continuously exchange moisture, heat, and carbon with the atmosphere; this affects the weather patterns and influences subtle climate changes on Earth.

With 70 percent of the Earth’s surface covered with water, the oceans are the Earth’s largest water supply. The oceans absorb and store heat, and these two factors play a huge role in how the oceans affect Earth’s weather.

The warmer the oceans get, the more water evaporates into the air, and when moisture-filled air blows over land, it will produce heavier rainfall and storms.

The oceans affect Earth’s climate by absorbing solar radiation and releasing heat necessary to drive the atmospheric circulation.

The oceans release moisture in the air that influences cloud cover and rainfall. It also absorbs carbon dioxide from the atmosphere and stores it for millions of years.

It also absorbs most of the solar energy that reaches Earth, and because water can store heat, the oceans slowly release that heat over time.

Temperature fluctuations at the coast throughout the year are minimal, much smaller than inland. That happens because inland areas heat up during the day but cool down quickly at night, and the ocean contains heat stored during the day, releasing it much slower than land. 

How Do Ocean Currents Affect the Climate?

Ocean currents are the movement of ocean water in an uninterrupted flow. Ocean currents are created by Earth’s rotation, tides, surface winds, salinity gradients, and temperature.

Ocean currents can also influence the rainfall on the coast. Water from warm ocean currents is more quickly evaporated, resulting in higher rain in nearby coastal areas.

Ocean currents behave like conveyer belts, moving warm water from the equator to the poles and bringing cold water from the poles back to the tropics.

Ocean currents affect climate and help counteract the uneven distribution of solar radiation that reaches Earth. Ocean currents are a significant factor that determines the climate of an area.

Main ocean current systems typically flow anti-clockwise in the southern hemisphere and clockwise in the northern hemisphere in circular patterns that follow the coastlines.

Without ocean currents, temperatures would be more extreme on Earth. The equator would be extremely hot and the poles extremely cold. Without ocean currents, Earth would be a lot less habitable for humans and animals alike. 

How Do Sea Breezes Affect Rainfall on The Coast?

When we talk about sea or land breezes, we refer to the breeze that blows onshore from the ocean to the land during the day and offshore in the evening.

In Summer, Sea breezes are typically stronger than in winter because of the significant temperature differences between the ocean and the land. Sea breezes can cause weather fronts along the coast and trigger daily rain and thunderstorms on the coast. 

The sun heats the ocean water and the land surface during the day. Ocean water absorbs energy from the sun, as does the land. However, water heats up slower than the land, so the air over the land is warmer than the air over the ocean.

When the warm air over the land rises continuously during the day, it causes low pressure at the surface. Over the ocean, a high surface pressure forms because of the cooler air temperature. This air tries to compensate and sinks lower over the ocean, and as the wind blows from the high pressure over the water to low pressure over the land, it creates a sea breeze.

How strong a sea breeze depends on the temperature difference between the ocean and the land. At night, the roles are reversed; the air over the ocean is warmer than the air over the land.

The land quickly loses heat after sunset, and so does the air above the ground. The ocean can hold its heat after sunset longer. This causes the low pressure to move over the ocean and the high pressure to move over the land.

This creates temperature differences between the ocean and the land, and the breeze will blow from the land to the ocean, which is why it is called a land breeze.

These sea breezes typically cause rain and thunderstorms on the coast. These sea breezes are very beneficial to the climate on the coast.  

Does it Rain More on The Oceans?

Earth’s oceans get 70 % rainfall per year, while the other 30 % fall on the continents.  Rain over the ocean is higher than on land, and rainfall levels commonly observed over the tropical areas of Earth are higher. Rainfall over the ocean affects the physical processes that influence climate and weather from basin-scale to micro-scale. Rainfall over the ocean affects significant circulation patterns and currents.

If no clouds formed over the ocean, rain would be extremely rare, and Earth would soon become desert.  

Climate Change – Extreme Coastal Rainfall

Coastal areas worldwide are threatened by sea levels rising from melting glacier ice, but high rainfall on coastlines can change macroclimatic features that will also impact nearshore ecosystems.

Coastal areas are highly vulnerable to increased storm intensities, storm surges, and heavy rainfall. Low-lying coastal areas are flooded and damaged by extreme rainfall and storm surges that destroy marine ecosystems and property and threaten human safety each year.

Climate change can bring heavier rainfall to coastal areas as the sea surface, and air temperatures increase. Extreme rainfall will also increase flooding on the coast as the warmer temperatures in mountainous regions will lead to more runoff due to melting snow.

The frequency and intensity of rainstorms at the coast will impact and worsen problems that already exist in coastal areas like declining coastal ecosystems, shoreline erosion, flooding, and water pollution.

The highly populated U.S coastline with approximately 25 million people is already vulnerable to coastal flooding. The rise in ocean temperatures will significantly affect coastal areas and humankind.

Why Do Coastal Areas Get More Rain 01

Why is Rain Not Salty?

We have established that rain comes from the ocean, so why is rain not salty? Seawater evaporates under the sun and moves into the atmosphere as water vapor; the salt stays behind in the sea.

The pure water vapor eventually condenses into a cloud droplet and rains down as salt-free water droplets. 

Defining Coastal Area Climate

The climate of a coastal area is defined by several weather conditions, which merge to form atmospheric conditions unique to coastal areas.

The weather conditions that define a coastal climate connected to a coastal area are:

  • Substantially higher rainfall than inland areas. 
  • Sea breezes during the day.
  • Land breezes during the night.
  • Warm ocean currents.
  • Mild temperatures through the year.
  • Coastal fog during spring and summer. 

These characteristics are distinctive weather conditions found on the coast. The ocean takes longer to heat up than land and retains heat longer; this delayed release of heat plays a significant role in creating sea and land breezes and is responsible for the mild climate in coastal areas.

During summer, the air temperature over land warms up rapidly while the ocean stays cooler as it takes longer to warm up. During winter, the land cools down quicker than the ocean, and the ocean stays warm longer. These special weather conditions regulate the climate in coastal areas keeping the temperatures mild all year long.

Rainfall Key Words

  • Annual rainfall – How much rainfall does an area get each year. 
  • The water cycle – Explains how water rises into the air and back to Earth.
  • Condense – It happens when water turns from a gas into a liquid.
  • Evaporate – When water turns from a liquid into a gas.
  • Water vapor – Water when it is an invisible gas.
  • Precipitation – Water that falls from clouds. Hail, sleet, and snow are also precipitation.

Conclusion

Coastal areas have some unique weather conditions that are familiar to anyone living in or frequently visiting coastal towns. Rainfall at the coast is always higher than inland areas due to the ocean’s enormous influence on almost every aspect of the climate.

The ocean warms and cools slower than the atmosphere; coastal weather is more moderate than inland temperatures, with less cold and hot extremes. 

High-pressure areas form when ocean water is heated; the warm water evaporates into the atmosphere, condenses, and forms clouds, which causes more rain at the coast. Because the ocean is a large water body, it directly influences the amount of rainfall the coast receives.

It rains more in coastal areas because high-water evaporation from the ocean increases rainfall. If you were unsure before, we hope this article explains the reason why coastal areas get more rain.   

Sources


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