* Pressure: Magma exists under immense pressure deep within the Earth's crust. This pressure keeps the dissolved gases within the magma and makes it more viscous (thick and sticky).
* Volatiles: Magma contains a significant amount of dissolved gases like water vapor, carbon dioxide, and sulfur dioxide. These gases act as a kind of internal "foaming agent" that contributes to the magma's fluidity.
* Cooling and Degassing: When magma erupts and becomes lava, it experiences a rapid decrease in pressure and the dissolved gases escape into the atmosphere. This causes the lava to become more viscous and stiff.
Think of it this way: Imagine a can of soda. When it's unopened, the pressure keeps the carbonation dissolved and the soda is quite fluid. When you open the can, the pressure drops, the carbon dioxide bubbles out, and the soda becomes flat and less fluid. The same principle applies to magma and lava.
In summary: Magma is actually less stiff than lava because the pressure and dissolved gases keep it more fluid. As lava erupts and cools, it becomes more viscous and less fluid due to the loss of pressure and degassing.
