Weather Systems & Atmosphere

Air pressure, fronts, cyclones, and precipitation

Weather is driven by unequal heating of Earth's surface and atmosphere. Warm air is less dense and rises (low pressure forms); cool air is denser and sinks (high pressure). These pressure differences drive wind from high to low pressure. Fronts are boundaries between air masses: a cold front occurs when cold, dense air pushes under warm air — causes sharp temperature drops, brief heavy rain. A warm front occurs when warm air glides over cold air — brings slow, steady precipitation. Coriolis effect (Earth's rotation) deflects wind paths, creating the large-scale circulation patterns. Hurricanes form over warm ocean water (≥26°C): warm moist air rises rapidly, condenses, releases latent heat, further driving updrafts in a self-reinforcing cycle.