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Geology LibreTexts

4.2: Heat capacity, the ocean, and our weather

 

Solar radiation is responsible for warming up the Earth, and we rely on the Earth to hold on to this heat that comes in and regulate the flow. The amount of heat required to increase the temperature of a substance by 1 degree Celcius is quantified as heat capacity, and this value determines how well a substance retains the heat.

When you heat up a pot of water on the stove, which one heats up first: the pot or the water? The pot heats up faster! Although you are putting the same amount of heat on both substances, the pot responds quicker than the water because water has a high heat capacity. Heat capacity is a measure of the heat required to raise the temperature of 1g of a substance by 1 Celsius. In this example, water has a very high heat capacity, which means it requires a lot of heat or energy to change temperature compared to many other substances like the pot. 

Additionally to temperature, it takes a tremendous amount of energy to change the water molecules from one state to another. In Earth, we have all three states of water - solid, liquid, and gas - and they're actually resistance from going back and forth from one state to another because of water's heat capacity. This relates to our ocean since the presence of the ocean moderates our daily lives and weather quite a bit in California through the amount of water molecules in the air.

https://www.youtube.com/watch?v=aUfrhTUAGOw

 

Water has an especially high heat capacity at 4.18 J/g*C, which means it takes more heat to warm a gram of water. This is why, throughout the course of a warm summer day, the water in the ocean does not experience a significant change. Land, on the other hand, has a much lower heat capacity, which is usually less than 1 J/g*C.

If you're interested in more about specific heat, check this out:  http://oceanservice.noaa.gov/education/pd/oceans_weather_climate/media/specific_heat.swf

For these reasons, the ocean takes a long time to change temperature significantly, whereas land can heat up very quickly (think of the hot sand and cool water at the beach in the summer). Since air travels around, air temperature is also regulated by these principles. Air that is in contact with the ocean will be much cooler from energy transfer between water and air, while air that sits above land will heat up much more quickly. Therefore, coastal climates are much more temperate because a body of water is nearby to regulate the temperature and keep it more constant. In the hot days of summer, landlocked places such as the Midwestern United States are much warmer than coastal cities at the same latitude because the land gets heated quickly and can’t disperse the heat. Temperate coastal areas are regulated by the ocean through land and sea breezes, which fluctuate depending on the temperature differences.

Learn more about land and sea breezes here: http://www.classzone.com/books/earth_science/terc/content/visualizations/es1903/es1903page01.cfm?cha

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/sea/htg.rxml

Uneven heating of the Earth creates differences in pressure, which result in winds. The larger the difference between pressures, the stronger the wind is created. These pressure differences can also result in hurricanes, or spirals of wind. Hurricanes are conducive to conditions with warmer sea surface temperatures, which need to be above 26 degrees Celcius. When hurricanes hit land, they usually stop traveling because their humidity and temperature requirements are hard to maintain with the rapid changes in land temperature that occur.

 

http://www.hk-phy.org/contextual/heat/tep/temch03_e.html

http://science.nasa.gov/earth-science/oceanography/ocean-earth-system/climate-variability/