Period+7+Group+6

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

We know that water vapor is in the air because it sometimes condenses on surfaces when the air reaches dew-point and becomes saturated so that we can see it. The water vapor gets in the air through evaporation. I know this because we did a Water Vapor in the Air lab using an enclosed cup of ice and green died water so we could see if the water we saw was from inside or outside of the cup. The experiment tried draw condensation (liquid water) to the surface of the cup. We also did a Water on the Hand Lab to see how water evaporated by blowing on and waving our hand. In the enclosed cup experiment, the water vapor surrounding the cup had to give it's energy to the cold surface and be forced back into it's liquid form. That is how we knew that water vapor was in the air, because it appeared on the outside of the cup in it's liquid form. Through the water on the hand lab, we learned that the water we had on our hand disappeared into the air through evaporation. The heat source (or sun) quickens the molecular motion on the surface of the water and gives it so much heat it changes into gas form, becoming water vapor. It is then in the atmosphere until it condenses back into water. Humidity is the amount of water vapor in the air measured with a hygrometer in percent. I know this from the wet/dry bulb lab and the Dragon's Breath Article. Through the condensation and evaporation labs we knew that water vapor is in the air. We learned through the Dragon's Breath Article that humidity is the amount of water vapor in the air. We also learned that different temperatures of air can hold more or less water vapor. Warmer air can hold more water vapor than colder air because it expands. For every temperature, there is a set amount of water vapor it can hold. Relative humidity is the percentage comparing the amount of water vapor that is in the air to the amount of water vapor the air could hold. Dew point is the temperature at which air is saturated and condensation occurs. We learned this through the Temperature Dew Point lab, the Wet/Dry Bulb lab, and the Relative Humidity lab sheet. After we'd learned about relative humidity, we wondered, What would happen if the relative humidity reached 100 degrees? We discovered that it would mean the air is saturated or full to the point where it couldn't hold anymore water vapor. Air can hold more or less water vapor at different temperatures. Hot air expands, therefore it can hold more water vapor. Every temperature has a set and proven maximum amount of air it can hold. When the temperature of air has this much water vapor that is dew point. Clouds form when water vapor in the air saturates and reaches dew point, then condenses on a dust, smoke, pollutant, or other particle called condensation nuclei. Dew forms when the ground temperature drops, causing water vapor to reach dew point and saturate, condensing on a cold surface. We learned this through the Cloud In a Bottle lab, the Dragon's Breath article, and the Cloud article. We saw how when we applied pressure in a tube full of water vapor, causing the temperature to rise. The air expanded and held more water vapor. When we decreased the pressure, the temperature dropped. The air became saturated with water vapor and reached dew point. So, the water was forced to condense in water form on dust, salt, and smoke particles. They attached onto condensation nuclei. The condensation nuclei began to join to form the visible beginnings of a cloud. This is a simulation to show how clouds form in nature. The Sun heats the water from the Earth's surface. This causes the molecular motion to speed up and it changes into gas from; water vapor. This is called evaporation.
 * How can we determine that water vapor is in the air and how does it get there? What is humidity and what is dew point and how are each measured? How do clouds and dew form?**