Question

### Models of Solar Corona Heating

The temperature of the Sun's surface (photosphere) is approximately $5{}800\text{ K}$, yet the solar corona (the outermost layer of the solar atmosphere) reaches temperatures of over $1{}000{}000\text{ K}$. Scientists have proposed two primary models to explain how energy is transported from the relatively cool photosphere to heat the extremely hot corona.

Model 1 (Wave Heating Model)
This model proposes that magnetohydrodynamic (MHD) waves, specifically Alfvén waves, are generated by turbulent convective motions of plasma in the photosphere. These waves travel upward along magnetic field lines into the corona. Because the density of the solar atmosphere decreases rapidly with altitude, the amplitude of these waves grows until they become non-linear and damp, transferring their mechanical and magnetic energy directly into the coronal plasma as thermal energy. Under this model, heating occurs continuously and is distributed smoothly across magnetic loops.

Model 2 (Magnetic Reconnection Model)
This model, also known as the nanoflare model, proposes that coronal heating is driven by magnetic reconnection. The footpoints of coronal magnetic loops are constantly twisted and sheared by plasma movements in the photosphere, storing magnetic energy in the corona. When the magnetic field lines become highly tangled, they spontaneously break and reconnect in millions of localized, impulsive bursts called nanoflares. Each nanoflare releases energy that heats the surrounding plasma to temperatures exceeding $10{}000{}000\text{ K}$, which then cools down to the average coronal temperature. Under this model, coronal heating is highly episodic and localized.

Based on the models, which of the following statements best describes a key difference between Model 1 and Model 2 regarding how energy is released to heat the corona?