It is rainy in Southern California today so continuing on with ground effect. My first and only real experience at needing and losing ground effect was flying a helicopter out of Bishop Airport one hot summer day. Lifting off full of fuel and trying to keep turbine temps in the green, or only brief forays into the yellow, I was just a few feet off the ground building speed after departing helicopter pad, I was doing fine, until I moved off the pavement and was over taller grass. I immediately needed more power as the ground effect suddenly had disappeared.