Ghosts are more likely to manifest if the air is dry.
Ion generators charge the air with positive particles that may supply energy for ghosts to manifest.
Many air cleaners/purifiers send out an ionic stream that may contribute to manifestations.
Spirits can draw energy from electrical appliances, the atmosphere and from people.
Fear and anger are two very powerful emotions from which a spirit may draw energy.
If there is a lot of emotional stress in a home that is haunted, the spirit could be drawing from the negative emotional energy.
Our emotions may affect spirits the same way they do people.
Spirits can attach themselves to a person, place or object.
In most cases, ghosts were people too. They are just no longer constrained to physical bodies.
Though spirits may not communicate well with us, they know what we say and do.