Examples of diffusion include the dispersion of tea in hot water and smoke from a lit cigarette spreading in the air. Carbon dioxide bubbles diffusing from an opened bottle of soda cause the soda to become flat as it loses its carbonation.
The human body exhibits diffusion in digestion by transfer of oxygen from the lungs into the blood and from the blood cells into the muscles. It also occurs during pregnancy, as food and oxygen reach the fetus from the mother’s body.
When pouring a cup of hot liquid, such as coffee, the heat diffuses and heats the cup. A sugar cube placed in a liquid dissolves and diffuses throughout the liquid, sweetening it evenly without stirring. Helium balloons exhibit diffusion, deflating as helium is slowly lost from the balloon. The reason you smell perfume on another person is because it diffuses into the surrounding air.
Watering your plants diffuses the water into them so the leaves do not wilt. Leaves diffuse carbon dioxide from air pockets between the mesophyll cells to transfer it to the chloroplast.
Ocean currents exhibit diffusion in meteorology by diffusing warm waters around the equator. In areas where moist warm air rises within cold air, it creates water vapor that leads to rainstorms.