YRF Overcrowded trees are under competitive stress from their neighbors. Thinning may be done to increase the resistance of the stand to environmental stress such as drought, insect infestation or extreme temperature.
Rising global temperatures are expected to cause greater evaporation of water vapor into the atmosphere, primarily from the oceans. On one hand, we know that water vapor is a powerful greenhouse gas, so an increase in water vapor might be expected to produce yet more warming through an enhanced greenhouse effect.lobal warming accelerates evaporation, placing more water vapor in the air. More water vapor generates a a stronger greenhouse effect, since water vapor is a greenhouse gas. However, it may also lead to the formation of more clouds, which might help cool the planet by increasing Earth's albedo.
Introduce the process of condensation. If students do not know what the process of condensation is, you can tell them it is the opposite of evaporation. In evaporation, a liquid (like water) changes state to become a gas (water vapor). In condensation, a gas (like water vapor) changes state to become a liquid (water). Explain that as water molecules in the air cool and slow down, their attractions overcome their speed and they join together, forming liquid water. This is the process of condensation.