Why the sea is warmer than the land at night

 during the day the sea heats up slower than the land because it has a higher specific heat capacity. this means that alot of heat energy is needed to heat the sea. the land will heat up faster than the sea because it has a lower specific heat capacity so less heat energy is needed to heat it up. during the night the land will loose the heat faster than the sea due to fact that it has a lower specific capacity and less heat energy to loose. the sea however has alot of heat energy to loose so it would take a long time. thats why the sea is warmer at night. the material with the lower specific heat capacity will loose the heat faster than the material with the greater heat capacity. 
Hope this helps you ;)

Its decreasing because of illnesses