As already indicated this is a time lapse exposure of a night time launch highlighting the trajectory of the rocket. A human observer would see a point of light following this trajectory.
The trajectory looks like this due to the multiple factors that affect a rocket leaving the Earth for orbit and how they are balanced.
In order to achieve orbit the rocket needs to be traveling at roughly 7800 m/s parallel to the Earths surface. Much less than this and the rocket will fall back to Earth. But greater than this and the rocket will out run the curvature of the Earth and continuously fall around it.
At high speeds The atmosphere makes life increasingly difficult due to air resistance causing mechanical stress on the rocket and also friction causing energy loss to heat. So it is important to leave the atmosphere rapidly to minimise these effects.
The Earth's gravity tends to force flying objects back to the ground. So its important to reach orbital velocity as quickly as possible to minimise these gravitational losses.
The trajectory seen in the photos is a compromise between these three factors. The rocket starts by heading directly up to escape the deeper layers of the atmosphere, but shortly after launch it slowly starts to incline over towards being parallel to Earths surface so that it can start building up orbital velocity.
The higher it goes the less air resistance there is and the more it can afford to lean. Eventually the rocket is travelling at an steep angle that provides maximum horizontal velocity increase, whilst still providing sufficient vertical component to counteract gravity.
So straight up to start with counteracting forces 2 and 3 then increasingly inclined balancing forces 1 and 3, hence the curved appearance of the trajectory.
The light in the exposure also dims towards the top as at this point the rocket is rapidly getting further from the launch site and is dimming due to distance. The lower part of the curve in the first photo is obviously a reflection in water.