Here is a hodge-podge of explanations I think are worth knowing. They’re related to questions I have asked or been asked. Cheers to a little physics, chemistry, and electrical engineering.
Molecular form of chlorophyll.
When static electricity is discharged during a storm in the form of lightning, the presence of that energy releases nitrogen from grass and other green plants. Nitrogen is contained in the coloring agent chlorophyll, an organic compound also made up of magnesium, carbon, hydrogen, and oxygen (Orgo, anyone?). When the nitrogen bonds are broken by the added energy (an endothermic reaction), loose nitrogen molecules combine with oxygen and then react in the presence of water to eventually decompose into nitrates. Although the strength of the nitrates produced during a storm are still debated, they are largely attributed to increasing the green color of plants, providing an explanation for why grass and other greens appear slightly greener after a storm.
The electricity being transmitted through our power lines is stepped up to extremely high voltage in order to reduce energy loss over the distance it travels. Current and voltage are related by the power equation, which says that power (work done per unit time) is equal to voltage V multiplied by current I. This means that high voltage and low current can achieve the same amount of transmitted power that higher current and lower voltage would. Higher voltage is preferred because flowing current loses energy in the form of heat.
The brown guacamole on the left and the green guacamole on the right are both safe to eat. Adding a compound that will lower the pH, such as lime juice, allows the guac to retain its color over a longer period of time.
However, the stepped up voltage has enough energy to cause a different type of energy discharge known as corona discharge. When the strength of the electric field on the surface of the power line exceeds the breakdown strength of the surrounding air, the air molecules break apart and release energy in the form of sound and occasionally also in photons. This accounts for why some power lines audibly buzz or crackle.
And in the spirit of summer, guacamole turns brown over time because avocado oxidizes (loses electrons) in the presence of oxygen contained in our air. However, lowering the pH of the guacamole (aka making it more acidic) prevents the redox reaction from taking place. This is why adding lime juice to fresh guacamole prevents the guac from changing color.