fire
火 centers on fire itself: the visible flames, heat, and light produced by burning.
火 is a pictograph of a flame, with the modern form preserving the shape of rising fire and flickering sides.
The two small strokes look like sparks flying upward from a central flame. Picture a campfire with sparks rising: 火 is fire.
For カ, imagine a car catching fire: car -> カ, and the flames rise from the engine.
fire; flame; blaze
fireworks
conflagration; fire
heating power; thermal power
Mars (planet)
Tuesday
volcano
fire; conflagration
eruption; volcanic eruption
Tuesday
arson; setting fire
extinguishing a fire; fire fighting
burn; scald
cremation
gunpowder; powder
ignition; lighting; firing; setting off
ignition; combustion; catching fire
spark
burner; nozzle; origin of a fire
gunfire; fire
sacred fire; sacred flame
fire prevention; fire control; fireproofing
volcanic ash
firearms; guns
outbreak of fire
wartime fire
fireproof
burning low; waning; declining
light; lamplight
live coals (for firelighting)
small fire
Molotov cocktail; petrol bomb; gasoline bomb
pyroclastic flow
leaping flames; flying sparks
large fire
brazier; hibachi
fuse; pilot light
fuse
forest fire; wildfire; bushfire
fire extinguisher
instigator; originator; initiator; torch bearer; incendiary; agitator; troublemaker
fire insurance
fireworks display; display of fireworks