Which conditions are high air pressure systems usually associated with

Clear, dry weather.

Low air pressure system is associated with air that rises high in the atmosphere (which becomes colder and converted into water vapours). This results in wet and cloudy conditions.

On the contrary, high air pressure system is linked to settled air that does not rise high in the atmosphere. This brings clear and dry conditions as no condensation and precipitation occurs in this case.

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.