Stormlight

Stormlight (Alethi: Zeradoreh) is a form of gaseous Investiture associated with Honor and brought by the highstorms of Roshar until the True Desolation. A form of proto-Stormlight existed prior to the Shattering. Following the birth of Retribution and the start of the Night of Sorrows, Stormlight becomes inaccessible on Roshar.
== Origin ==
Stormlight comes directly from the Spiritual Realm, leaking into the Physical and the Cognitive as the three are brought closer together. This typically happens on Roshar during a highstorm. As the storm passes, any spheres exposed to it are infused with Stormlight near its end. At the same time, it arrives in Shadesmar as a wave of light high in the sky. There, spren absorb it directly.
Bondsmiths of third Oath or higher can likewise infuse spheres and people with Stormlight, though with significant effort. Dalinar is also able to open Honor's Perpendicularity to release functionally-infinite amounts of Stormlight over a vast area for a limited amount of time. This is, however, unusual, and possibly a consequence of Stormfather's particular nature as Honor's Cognitive Shadow.
In the present, it appears that the Stormfather -- and, by extension, Honor -- is the primary force enabling Stormlight to cross over into other Realms. However, it has existed prior to the Shattering. Back then, it had slightly different properties.
== Appearance and Properties ==
Stormlight appears as luminescent white vapor with a faint blue tint. When free, it behaves similarly to smoke, dissipating in puffs and leaving trails when its source moves. Gemstones left outside during a highstorm absorb it, becoming infused, which manifests as the gems glowing. The amount of Stormlight collected is not directly proportional to the strength of the highstorm.
Absorbed Stormlight, if unused, will eventually begin leaking out through miniscule cracks in the gemstones. The speed at which it leaks varies depending on its current vessel. A person can only hold Stormlight for a few minutes at most, while a gemstone will hold it for several days -- the ones used as currency glow for about a week, while bigger gems last a while longer. Perfect gemstones, like the King's Drop, can hold it for centuries, if not forever. When leaking from gems, Stormlight assumes their color. It can be transferred from one gemstone to another through various means, such as using tuning forks that resonate to Honor's pure tone. Aluminum cannot prevent Stormlight leakage, as it is leaking directly into the Spiritual Realm.
Stormlight is stored in gemstones similar to Voidlight, but these two types of light cannot be stored in the same gemstone. Stormlight leaks significantly faster than Voidlight. Even when stored in a sphere or gemstone, Stormlight (and other Lights, as well as spren) is unable to leave the Rosharan system due to its Connection. Mraize describes the vessel growing heavier and heavier the farther from Roshar it gets, eventually growing immovable. He also hints that he or the Ghostbloods have circumnavigated this issue, though he refuses to go into detail.
== Uses ==
=== Magic Fuel ===
Stormlight is the primary fuel of Surgebinding abilities for Knights Radiant and Honorbearers before the formation of Retribution. To absorb it, a Surgebinder breathes it in from sources such as gemstones or the highstorm itself. When inhaled, Stormlight gives the user a sensation of increased energy, restlessness and desire to move, with several people comparing it to a storm raging inside them. While held, it will automatically heal wounds, exhaustion and even conditions such as poisoning or drunkenness. If the Surgebinder is pregnant, then the child can also be healed by Stormlight. Stormlight doesn't give the Surgebinder much additional raw strength. It can also be consumed to power the use of Surges.
There are other methods of obtaining Stormlight, such as the method used by Vasher, which can be used by others. Stormlight can serve as replacement for other forms of Investiture, most notably Breath. A Returned can survive off consuming it. Likewise, Nightblood can be fuelled by Stormlight, and when unsheathed, will begin to absorb it from its environment before going for living beings. It's possible to transform Stormlight into Breath and use it in Awakening, though that is noted as extremely difficult, with neither Vasher, Vivenna, or Hoid having figured out how to achieve this so far.
Fabrials will not function unless the gems comprising them are infused with Stormlight.
=== Healing and Sustenance ===
Even for non-Surgebinders, Stormlight has minor healing properties. Rosharans are notably healthier than people from other planets, and fall sick less often because there is generally more Investiture around. Plants can also be encouraged to grow more quickly by placing Stormlight-infused gems nearby. 
Stormlight is also important to Roshar's native beings. Creatures with gemhearts require it, presumably to fuel their spren bonds, and large quantities of it are necessary for them to transform. Among others, chasmfiends pupate in areas that are highly exposed to highstorms, and singers need highstorm levels of Stormlight to change form. In Shadesmar, spren derive sustenance from Stormlight, and tend to become more lively and energetic in its presence.
=== Farming ===
Stormlight can be used to fuel the growth of plants directly. This farming technique involves beating drums to a certain rhythm next to emeralds infused with Stormlight. This attracts lifespren which will in turn carry Stormlight back and forth to nearby crops, boosting their growth. The emeralds used will periodically crack and it is currently unknown whether Soulcasting can produce more grains using the same amount of emerald. The Parshendi used to do gemheart hunts on the shattered plains for this specific purpose. This method was unknown to humans until Rlain revealed it. 
=== Currency ===
The spheres used as money across Roshar are generally considered more valuable when infused. While nominally they're worth the same whether dun or glowing, merchants will often find dun spheres suspicious, and will call an expert to verify if a dun sphere isn't counterfeit. Moneychangers capitalize on this, exchanging dun spheres for infused ones or taking spheres to be infused in their secured nets -- for a fee. The value of infused spheres rises even higher with the return of Surgebinding, with some people making a tidy profit off trading spheres with Urithiru.
Stormlight is directly used as a currency in Roshar's Cognitive Realm, with moneychangers in Celebrant storing it in perfect gemstones. A device is used to transfer Stormlight from smaller gemstones into the perfect ones, and in exchange, one receives credit which can be spent in the city.
== See also ==
* Voidlight - gaseous form of Investiture associated with Odium
* Breath - gaseous form of Investiture associated with Endowment
* Mists - gaseous form of Investiture associated with Preservation
* Lifelight - gaseous form of Investiture associated with Cultivation
== Notes ==
category: currencies