Temperature of Ocean Water| Class 11 Chapter 12 Geography Notes

The ocean water temperature is directly affected by the amount of radiation received from the sun on the ocean surface. The latitudes are closer to the equator and receive direct sunlight all over the years the ocean surface is warmer in these regions where sunlight falls.

The ocean temperatures are different in terms of depth and longitude. There is an inverse relation between the depth and temperature of the ocean. Wherever in the ocean if the depth is deeper than the lower the temperature would be.

In this article, You will learn about the Temperature of ocean water, the Horizontal and Vertical distribution of the ocean temp, and many more related to the topic.

The horizontal distribution of ocean temperature has an impact on global climate patterns, ocean circulation, and marine ecosystems. It plays a role in weather patterns, the formation of tropical cyclones and the distribution of marine life.

• The average surface water temperature of the oceans is around 26.7°C (80°F).
• This temperature gradually decreases as you move away from the equator towards the poles.
• The rate of decrease is typically around 0.5°C per degree of latitude.
• So, at 20° north and south latitudes, the average temperature is around 22°C (71.6°F), at 40° it’s around 14°C (57.2°F), and near the poles, it can approach freezing.
• Factors that affect the horizontal distribution of the ocean temperature are Sunlight, Ocean currents, Prevailing winds and Landmasses.
• The northern hemisphere has a slightly higher average ocean temperature compared to the southern hemisphere.
• This is because the northern hemisphere has more landmass, which tends to absorb more heat from the sun during summer and release it back into the atmosphere during winter.

The vertical distribution of ocean water is measured from the ocean’s surface to the bottom of the ocean floor; with the gradual increase in the ocean’s depth, the temperature of the ocean water decreases.

• The surface zone’s topmost layer is typically 50-200 meters deep.
• Relatively warm and well-mixed due to wind and wave action.
• Temperature closely follows atmospheric conditions and varies with latitude.
• The thermocline transition zone between the surface and deep water.
• Depth varies (100-400 meters) but is characterized by a rapid decrease in temperature with depth.
• Acts as a barrier, limiting heat exchange between surface and deep waters.
• Deep ocean Vast majority of ocean volume lies below the thermocline.
• Temperature remains relatively constant (around 1.5°C to 4°C).
• Temperature changes are very slow due to minimal sunlight penetration and slow water movement.
• Factors affecting the vertical distribution of Sunlight Penetration, Water Density and Ocean Circulation.

• Earth is about 70.8% water and 29.2% land.
• The northern hemisphere has more landmass compared to the southern hemisphere, affecting ocean temperature patterns.
• While water covers most of the planet, it’s not evenly distributed.
• Only 3% of Earth’s water is freshwater suitable for human consumption.
• Most freshwater is locked away in glaciers (69%) and groundwater (30%).
• Lakes, rivers, and swamps hold a very small percentage of less than one per cent of freshwater.
• The land is not evenly spread out either.
• Large continents like Eurasia and Africa dominate, while smaller land masses are scattered across the globe.

Impact of Unequal distribution of land and water

• Water Scarcity: Uneven freshwater distribution leads to water scarcity in many regions, impacting agriculture, human health, and ecosystems.

• Climate Patterns: The unequal distribution of land and water influences global climate patterns. Land heats and cools faster than water, affecting ocean currents and atmospheric circulation.

• Sea Level Rise: Melting glaciers due to climate change can contribute to rising sea levels, threatening coastal communities and ecosystems.

• Biodiversity: Landmass distribution influences the distribution of biomes and ecosystems.

Prevailing winds, the dominant winds that blow in a particular region, significantly impact ocean temperatures.

• When prevailing winds blow away from the shore (offshore winds), they drag warm surface water outwards.
• This creates a vacancy near the coast.
• To fill this gap, colder water from deeper ocean layers rises towards the surface in a process called upwelling.
• Upwelling brings nutrient-rich cold water to the surface, which boosts marine productivity by fueling phytoplankton growth and creates cooler coastal regions compared to what surrounding water temperatures would suggest.
• Conversely, onshore winds (blowing towards the shore) can push warm surface water towards the coast, causing it to pile up.
• This leads to warmer coastal waters compared to offshore areas.

Examples :

• California Current: Prevailing winds blowing south along the west coast of North America cause upwelling, creating cool and nutrient-rich waters ideal for marine life like kelp forests.

• Peru Current: Strong southerly winds off the coast of Peru trigger upwelling, bringing cold, nutrient-rich waters to the surface, creating a highly productive fishing zone.

Ocean currents are massive, continuous movements of seawater driven by various forces. Ocean currents are like rivers in the sea, but instead of freshwater, they transport vast volumes of saltwater. They flow in predictable directions and influence everything from climate patterns to marine life distribution.

• Types of Currents: Ocean currents can be categorized based on their location and depth:
  1. Surface Currents: Flow in the upper ocean, primarily influenced by wind and the Coriolis Effect. Examples include the Gulf Stream and Kuroshio Current.
  2. Deep Currents: Move slowly in the deep ocean, driven by density differences. They play a crucial role in global heat transport and ocean circulation.
• Driving forces that combine to create ocean currents are Wind, the Coriolis effect, water density, Earth’s Rotation and Tides.
• Ocean currents have a global significance or impact on the planet such as climate regulation, marine life, weather patterns and coastal processes.

• Examples of Major Currents that an follows impact on the planet are as following :
  1. Gulf Stream (Atlantic): Carries warm water from the tropics to Western Europe, moderating its climate.
  2. Kuroshio Current (Pacific): Warm current bringing mild temperatures to the east coast of Japan.
  3. California Current (Pacific): Cool current rich in nutrients, creating ideal conditions for kelp forests off the west coast of North America.
  4. Peru Current (Pacific): Brings cold, nutrient-rich waters to the surface, creating a highly productive fishing zone off the coast of Peru.

There are many factors that directly or indirectly affect the temperature of the ocean water. The ocean temperature is not the same everywhere.

It is warmer near the equator where the sun shines brightest and colder closer to the poles where it’s icy. The water on top is also warmer than the deep, dark parts down below. Winds and ocean currents can also stir things up, making some coastal areas cooler or warmer than you might expect.

Also Read

• Ocean Currents
• Ocean and its Current
• What is ocean current?

What is the temperature of the ocean?

These variations in solar energy mean that the ocean surface can vary in temperature from a warm 30°C (86°F) in the tropics to a very cold -2°C (28°F) near the poles.

What is the mean temperature of the ocean?

Ocean Mean Temperature(OMT) is measured up to a depth of 26 degrees isotherm. It is measured with the help of satellites that orbit the earth. In the Indian ocean, OMT is analysed by measuring the ocean thermal energy during the period from January to March.

Why is ocean temperature high?

The ocean absorbs most of the excess heat from greenhouse gas emissions, leading to rising ocean temperatures. Increasing ocean temperatures affect marine species and ecosystems, causing coral bleaching and the loss of breeding grounds for marine fishes and mammals.

Which ocean water is coldest?

“Antarctic bottom water” is the coldest, saltiest water on the planet. These waters play a crucial role in the ocean’s ability to act as a buffer against climate change by absorbing excess heat and human-caused carbon pollution.

What is the highest temperature of the ocean?

Experts have pointed to a reading of 99.7 degrees Fahrenheit, recorded in the middle of Kuwait Bay in 2020 and reported in a 2020 research paper, as the world record to date.