Stagnation pressure is the pressure that a fluid would have if it was brought to rest adiabatically (without gaining or losing heat) by a reversible, isentropic process.
Static pressure is the pressure that a fluid exerts on a surface when it is at rest, while stagnation pressure takes into account the kinetic energy of the fluid due to its motion.
Stagnation pressure can change due to changes in velocity, temperature, and density of the fluid, as well as changes in the geometry of the flow.
An increase in velocity leads to an increase in stagnation pressure, as the kinetic energy of the fluid increases and is converted into stagnation pressure.
A decrease in temperature leads to an increase in stagnation pressure, as the decrease in temperature causes a decrease in the kinetic energy of the fluid, which is then converted into pressure. On the other hand, an increase in temperature can decrease stagnation pressure due to a decrease in fluid density.