Answer:
It is a well known fact that the earth rotates around the sun in an inclined axis which is approximately 23 degree. The inclined nature of earth axis causes variation in the solar heat received at any place on the earth surface. The hemisphere facing the sun due to this axial tilt, gets higher sun energy as compared to the opposite side. The hemisphere which faces the sun will experience summer whereas the hemisphere away from sun will experience winter.
In each of the hemisphere the polar areas will receive higher radiation and longer daytime during the summer season. However it has been observed that there is difference in radiation received at different areas of earth surface and radiated. The tropical areas have lower reflectance and thus a large part of incoming solar radiation have been absorbed along the tropics. The poles though have longer daytime during summer and hence greater solar radiation but due to high reflectance radiate more energy. Thus the tropical areas have surplus energy as compared to deficit energy areas of poles. This difference in energy creates a heat imbalance.
This net heat difference between poles and equator gives rise to a global circulation system leading to flow of heat from the net energy excess areas to deficit areas. This circulation takes place through atmosphere as well as oceans and different process of climate viz. evaporation, transpiration, rainfall, wind, convection, oceanic circulations etc work as tools of this system
Relay contacts that are defined as being normally open (n.o.) have contacts that are open only if the relay coil is known to have de-energized.
<h3>What is meant by normally open contacts?</h3>
Normally open (NO) are known to be open if there is no measure of current that is flowing through a given coil but it often close as soon as the coil is said to be energized.
Note that Normally closed (NO) contacts are said to be closed only if the coil is said to be de-energized and open only if the coil is said to carry current or is known to have energized.
The role of relay contact is wide. The Relays are tools that are often used in the work of switching of control circuits and it is one that a person cannot used for power switching that has relatively bigger ampacity.
Therefore, Relay contacts that are defined as being normally open (n.o.) have contacts that are open only if the relay coil is known to have de-energized.
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