In simple terms, insolation can be defined as the incoming solar radiation from the sun, which is received on earth in short waves. As the size of the earth and its distance from the sun are both relatively small, it receives significantly less quantity of insolation. Only two billionths of a percent of total solar radiation reach the earth’s surface, which is two units of energy out of 1,000,00,000 units of energy radiated by the sun! This small part of solar radiation is critical, since it is the primary source of energy on the planet for most physical and biological processes. Furthermore, a small amount of insolation is also absorbed by dust particles, ozone, water vapour, and other gases in the atmosphere.

Major Characteristics of Insolation

Having understood what is insolation, let’s know more about its fundamental characteristics: 

• Only 51% of the sun’s insolation reaches the earth’s surface.
• The atmosphere reflects 35% of the remaining 49% into space.

Factors Influencing Insolation

The sunlight Earth gets isn’t spread out evenly; it plays favorites depending on where you are. Think of it like this: the tropics get the most annual sunlight, and it slowly gets less as you move towards the poles. Also, winter gets a bit of a cold shoulder compared to summer when it comes to sunshine. There are a few factors that decide how much sunlight a place gets, and they kind of act like influencers in the world of weather.

Incidence Angle:

• Think of the Earth like a giant ball, and the sun’s rays hit it at different angles depending on where you are.
• When the sun is right above, the rays come straight down and focus on a small area, giving us more sunlight and warmth.
• If the sun is at an angle, the rays spread out over a larger area, giving us less sunlight and warmth.

Sun Rays Traveling Through the Atmosphere:

• When the sun is low in the sky, its rays travel through more of our atmosphere.
• The atmosphere can reflect and absorb some of this heat, so the longer the journey through the atmosphere, the less intense the sunlight at a specific location.

Duration of the Day:

• Depending on where you are and the time of year, days can be longer or shorter.
• The length of the day affects how much sunlight we get – longer days mean more sunlight.

Atmosphere’s Transparency:

• The atmosphere, our air, can either help or hinder sunlight.
• If there are clouds, dust, or water vapor in the air, they can block sunlight.
• Thick clouds, for instance, can act like a blanket, keeping sunlight from reaching us.
• On clear days, sunlight easily reaches the surface.

Heating and Cooling of the Atmosphere

Four different heating processes cause the heating of the atmosphere, viz—Radiation, Conduction, Convection and Advection.

Radiation: Think of radiation as the way Earth gets warmed up by the sun. It’s like the sun sending out invisible waves of heat, and when these waves reach Earth, they make it warm. This process also happens when Earth releases heat back into space.

Conduction: Imagine conduction like passing warmth from a hot object to a cooler one when they touch. For example, when the air meets the ground, heat can transfer from the warmer ground to the cooler air through direct contact.

Convection: Convection is like the air itself moving to carry heat around. Picture hot air rising and cooler air sinking. This vertical movement helps distribute warmth in the atmosphere, like how a fan spreads air in a room.

Advection: Now, advection is like the horizontal movement of warmth by the wind. If warm winds blow over a place, it gets warmer there. On the flip side, if cold winds pass through, the temperature drops. It’s like the wind delivering different temperatures as it travels.

Conclusion

We know that the sun is like Earth’s main energy buddy. Insolation, which is just a fancy word for the sun’s energy, comes to Earth in short waves. How much of this sunshine we get depends on three things: the angle it’s coming at, how long the day is, and how clear the sky is. Now, when it comes to warming up and cooling down our atmosphere, think of it like this: there’s radiation, conduction, convection, and advection – these are the cool processes that make our weather dance!

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