Period+2+Group+7

Period 2 Group 7 Response to Investigation 6 Essential Question(s)

=How can we determine that water vapor is in the air?= You can determine there is water vapor in the air by looking for condensation on a surface cooler than the air. In class we did a ice water, and room temperature water lab. This lab showed that the surface of cooler water cup was able to absorb the water vapor in the air, opposed to the room temperature water cup surface. This happened because energy transfers from hot to cold. The water vapor in the air was warmer than the cooler cup. This means the water vapor had more molecular more motion, hence it is a gas (water vapor). The water vapor transfered energy to the cooler cup, decreasing the molecular motion in the water vapor. This turned the water vapor back into a liquid form. Now, you are left with condensation on the side of your cooler surface, proving there is water vapor in your air. =How does what vapor get into the air?= Water vapor gets into the air by evaporation. In class we did a lab where we put water on the back of both of our hands to show how water evaporates. While we had water on both our hands, one hand stayed still and untouched, while we blew on the opposite hand. The water on the hand that was blown on disappeard (evaporated) and appeared physically cooler, while the water on the other hand still remained the same. How did this happen? Well after further analysis of this lab, we came to the conclusion that the water on the hand that we blew on took energy from both the air being blown, and the energy from our hand to evaporate. In other words, seeing as the water started out in a liquid state on our hands, in order to gain more molecular motion to become a gas and evaporate into the air, it needed more energy in order to do so. Thus, proving that water vapor gets into the air by evaporation. =What is humidity and how is it measured?= Humidity is the water vapor in our air. Relative humidity is amount of water vapor in our air. We measure relative humidity in percentages with a hygrometer. In class we did a packet on humidity to help emphisize what exactly humidity is and how it is measured. The packet told us that relative humidity is how saturated (full) the air is in a given temperature. Different temperatures hold different amounts of water vapor. For example, warmer air holds more water vapor than cold air, due to the air's densities. The packet also taught us that relative humidity is measured with a hygrometer. A hygrometer measures the difference between the regular air temperature, and the temperature of a wet bulb in the regular air. The difference between the two temperatures and the dry bulb readings are compared. The imformation is used to determine how much water vapor is in the air, which is given out in a percent. This is how they measure humidity.
 * What is humidity and what is dew point and how are each measured?**

What is dewpoint and how is it measured?
Dewpoint is the temperature at which air is saturated, otherwise know as the temperature at which condensation can happen. In the article 'Dragon's Breath' it explained that dewpoint is the temperature at which the air is at 100% humidity, or is fully saturated. When air reaches dewpoint, only then can condensation happen. The article also explained that you measure dew point with hygrometer. Not only does a hygrometer measure humidity, but it also measures dew point because dewpoint is when the air is 100% saturated, or at 100% humidity.

**How do clouds and dew form?**
Clouds form when water vapor in the air reaches dewpoint and condenses onto condensation nuclei, making clouds visible. In class, we did a cloud lab in a soda bottle to help explain this phenomenon. As water vapor travels higher into the troposphere and the temperatures begin to drop, the air becomes saturated because cooler air is more dense, meaning it takes less water vapor than warm air to reach dewpoint. To show this in the lab we applied more pressure in the bottle, making the air more dense, which helped the water vapor reach dewpoint. Once the water in the cooler, denser air reaches dewpoint then it condesnses onto condensation nuclei in the air. Condensation nuclei are small particles in the air in which water vapor can condense on. To show this in our lab, we applied smoke particle to the air. So if you add all those factors together you get a visible cloud.