Period+7+Group+7

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

You can tell that water vapor is in the air by setting up a lab or experiment that will bring the water vapor back into a liquid form that will consist of a cup, water, ice, food coloring, and plastic wrap; water vapor gets in the air by evaporation. We learned in our "What's in the Air" lab how to do the experiment. When my group set up our lab we first put the water in the plastic cup mixed with food coloring, next we put some ice in the colored water then sealed it with plastic wrap, after a while my group saw that fog or a moist substance was on the sides of the cup; the water wasn't green meaning that water vapor must have come to the sides of the cup and turned back into a liquid. The process starts out by first the warm water vapor touching the cool surface of the cup (because of the ice) transferring it's heat energy to the surface and because it is losing heat (molecular motion) it will start to condense and turn back in to a liquid on the sides of the cup. Also in this lab there was a little stove with a cup of water which showed how when the molecules gained energy and sped up they will have gained enough molecular motion to rise up and turn into the gas form of water, water vapor; this is an example of 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?**

Humidity is the amount of water vapor in the air, and dew point is the temperature at which the water vapor will turn back into a liquid, in other words the temperature the air is saturated at. We know about this information because in the article "Dragon's Breath" it explained what dew point and humidity are. We also know what dew point is because of the Condensation and Dew Point Lab we did in class which gave my group a better understanding of what dew point is. Dew point is also known as condensation. When water is heated and it evaporates into the air, the water vapor will eventually rise up and touch a cool surface and transfer it's energy to the cool surface and then the water vapor will condense because it has lost it's heat forming dew. When the air is warm, it means that the air can hold more water vapor, meaning the air is humid, and if the air is cold, the air can not hold as much water vapor meaning it is less humid.

Relative humidity is measured by using a hygrometer and a 2-bulb-thermometer (with a Relative Humidity Calculator), and dew point is measured by using a weather balloon with a radiosonde attached to it; the radiosonde also measures temperature and air pressure. Wind speed and direction are also caculated from the tracking data. My group knows this information because in Investgation 1 my class used a hyrometor which measured the relative humidity in the air. Also,for the 2-bulb-thermometer, one bulb will be wet and when the temperature is read, you have to subtract the difference between the wet bulb and the dry bulb, then with the Relative Humidity Calculator, you have to go down the left side for the dry temperature reading, then go right the same number of times as the subtracted readings of the wet and dry temperatures, the place you stop should be the relative humidity % (percentage).My group knows that dew point is measured with a weather balloon (with a radiosonde) because in class we watched a video explaining how a radiosonde works and what it measured which included dew point, temperature, air pressure, and relative humidity as well. Weather balloons are sent in to the air 2 times a day at the same time. The balloons rise up to about 30km in the air,then pop, and the radiosonde falls down back to earth with a parachute attached to it. When the temperature increases and the amount of water vapor stays the same, the relative humidity decreases. When the temperature stays the same but water vapor increases, the relative humidity increases.

Condensation is the reason clouds and dew forms.My group knows this because we read an article called "Dragon's Breath" which said that dew forms because of condensation, and when the temperature goes even a tiny bit lower then dew point, water condenses to form ice crystals, dew, fog, or clouds. My group also knows how dew forms because of the "What's in the Air?" lab which showed dew(all foggy and moist) on the sides of the cup. Another reason my groups knows how a cloud forms is because of the demonstration/lab we did in class which showed the beginning step of how a cloud forms (in a soda bottle). In the lab that showed how a cloud formed, the first step was to to fill a soda bottle with a little water, then shake it up really good. When the bottle is done being shook, you insert a lit match inside the bottle very quickly then tightly shut it, trying not to shake it. The last steps are to squeeze the bottle(compress) then after a little time, let go and you will see fog on the inside of the bottle. The reason you shook the bottle is because the result of it was to increase the molecular motion inside the water eventually turning some of it in to water vapor, then when you put the match inside the condensation nuclei/smoke particles gave a place for the water vapor to condense on. The warmer the air the more water vapor it can hold, and the cooler it is, the less water vapor it can hold.