In hydrological cycle, water vapor is produced both from ocean as well as inland areas by evaporation and evapo-transpiration respectively. But why more precipitation occurs on inland areas? Please discuss.
Dr. Phanibhusan Ghosh
Hello Sir,
Coastal belts, mangroves, mudflats, inland forests all contribute towards the formation of clouds. Aerosols containing algal fragments, exuviae, slat ions; DMSO from DMS of the coastal belts, seagrass meadows, mudflats and phytoplankton; DMSO and formaldehyde from magroves and other macrophytes; methane from the aforemntioned areas and dust/pollutants (along with other more dicussed ones, pollen from all the plants) from landmass all serve as cloud condensation nuclei which coupled with the temperature differences over terrestrial landmasses compared to the more stable ocean surface provides the thermodynamic nudge resulting in density differences of the evapo-transpired load. The result of which is apparently higher precipitation. The proximity to a source of water also governs the rate of precipitations as inland deserts (like Taklmakan) receive rainfall at decadal scales and one cannot consider them being recepients of greater precipitation compared to oceans, while the Namib desert (being a coastal desert) receives the daily dose of condensed fog in the early morning in spite of receiving very meagre rainfall. I mentioned 'apparent higher precipitation' in my answer while discussing about the dissimilar distribution of precipitation over inland areas and ocean because if we truly comprae the rainfall data received by these two segments of the world annually then I believe the scale will tip towards the ocean because of all the tropical stroms of which only the scaled down versions are received by the landmass as most storm cells drastically lose energy priot to landfall and the quantity of rainfall over sea remains eluded or become downsized in term of the precipitation per unit area due to the immensity of ocean surface compared to any land mass.
With regards,
Dr. Abhishek Mukherjee
Coastal areas on an average receive more rainfall than the inland areas. The reason behind it is that there is a high evaporation in the sea, so when the wind blows from sea to land(sea brezzes), they carry moisture with them
Hi,
There must be an orographic effect. When air flows over continents, it must rise in altitude. As the air rises, its pressure and temperature decreases (perfect gas law). As air cools, it becomes saturated with water vapor, leading to precipitations.
Best regards.
Matthieu Roy-Barman
Matthieu
Oceans contribute more in supply of moisture since evaporation is high. But formation of precipitation needs some other conditions such as lifting of air masses to high altitude and falling temperature (up to dew point) and condensation. Land surfaces support more on lifting saturated air (e g. Orographic lifting over the windward slopes of mountains) and condensation due to availability of more nuclei in the atmosphere. Those may be the causes of having more precipitation on the land surface than on seas.
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