Always look to the shadows and catchlights.
One & two are fairly hard light but not hot-shoe flash hard. Look how the edges of the shadows are slightly soft. Could be a small softbox at over 3 times the diagonal away from the subject.
The light for one and two are above and camera left.
Three is flat light, probably an overcast day as hotdog says.
Four is again fairly hard light located high and camera left - look at the shadow her right arm and shoulder throw on her chest. This light is a bit softer than for 1 & 2.
Living and loving it in Pattaya, Thailand. Canon 7D - See the gear list for the rest.