breath, air, steam, gas, weather, used in Taoist charms
炁 centers on invisible, flowing substances: breath, air, steam, or gas. The weather and Taoist charm senses extend from the idea of vital energy or atmospheric force.
炁 is an older variant of 気, combining 旡 (a person exhaling) with 灬 (fire), suggesting breath or vapor rising from heat. The exact historical development is uncertain, but it is associated with Taoist concepts of vital energy.
The top 旡 looks like a person with an open mouth, and the bottom 灬 is fire. Imagine a person's breath becoming visible as steam rising from a fire: that's air, gas, or vital energy.
For キ, picture a key made of steam: a key -> キ, unlocking the invisible power of breath and air.