Explain the following terms:
$(a)$ Heat convection
$(b)$ Sea breeze

(N/A) $(1)$ Propagation of heat in fluids is due to heat convection.
When a fluid is heated from the bottom, the volume of the fluid in that part increases and consequently, the density decreases.
Due to the force of buoyancy, the lighter fluid rises upward and the cooler fluid moves down to take its place.
The whole fluid gets heated as a result of such a continuous process. This process of heating is called "heat convection".
Heat convection can be natural or forced.
Natural convection: If the motion of the fluid takes place due to a difference in density, it is called natural convection.
In the atmosphere, hot and cold air currents are formed by natural convection due to unbalanced heat flow.
Forced convection: If the motion of the fluid takes place with the help of some device like a pump, fan, stirrer, etc., it is called forced convection.
In the human body, the heart acts as a pump and by circulating blood in all parts of the body, it maintains the temperature of the body by forced convection.
$(2)$ Sea breeze:
During the day, the ground heats up more quickly than large bodies of water. This occurs because water has a greater specific heat and mixing currents disperse the absorbed heat throughout the large volume of water.
The air in contact with the warm ground is heated by conduction. It expands, becoming less dense than the surrounding cooler air.
As a result, the warm air rises (air currents) and other air moves (winds) to fill the space, creating a sea breeze near a large body of water.
Cooler air descends, and a thermal convection cycle is set up, which transfers heat away from the land.
At night, the ground loses its heat more quickly, and the water surface is warmer than the land, leading to land breeze.