Investigation 4: Moisture and Clouds
- Page ID
- 40377
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Have you ever wondered how a cloud, which consists of trillions of tiny liquid droplets, is able to form almost out of "thin air?" Or why dew can spontaneously form on surfaces in the middle of the night (Figure 4.1)? How about why you can have a "bad hair day?" All of those have to deal with an interesting fact about our atmosphere: It consists of 78% Nitrogen, 21% Oxygen, and at least some Water Vapor (between 0-4%). Indeed, the air that you are breathing right now consists of a certain amount of water vapor (also referred to as "moisture" in this investigation) in addition to the other gasses you are taking in. This investigation explores the role that moisture plays in relative humidity, temperature, and cloud formation.
- Discern how air temperature influences relative humidity.
- Investigate the effects of air pressure on humidity.
- Determine where in the atmosphere are clouds present on a Stuve Diagram.
- 4.1: What is Relative Humidity?
- We introduce humidity as the moisture in the air, influencing comfort levels and characterized mainly by Relative Humidity, which is the ratio of actual vapor pressure to saturation vapor pressure. It notes that vapor pressure varies with actual moisture, while saturation vapor pressure is temperature-dependent. Higher temperatures increase moisture capacity, and meteorologists use tables and equations to quantify saturation vapor pressure.
- 4.2: Relative Humidity Diurnal Cycle
- We discuss how daily temperature fluctuations affect relative humidity, noting that higher temperatures lead to decreased relative humidity and vice versa at night. It presents data from De Anza College and calculations linking relative humidity to vapor pressure, illustrating the inverse relationship with graphs from Moffett Field showing temperature, dew point, and relative humidity trends.
- 4.3: Saturation and Clouds
- Introduces Dew Point Temperature, the point at which air reaches saturation with moisture. A higher dew point means less cooling is needed to form clouds, while a lower one requires more cooling. It features a hands-on experiment, "Cloud in a Bottle," to demonstrate cloud formation, and notes that saturated air near the surface causes fog, while saturation above results in clouds. Safety precautions for the experiment are also included.
- 4.4: Clouds in the Vertical Atmosphere
- We discuss how upper-level clouds form when air temperature and dew point are similar, causing saturation. It describes cumuloform clouds (from rising air) and stratoform clouds (from moisture influx). Observations from Greensboro, NC, and Blacksburg, VA, show saturation at certain heights, while Oakland, CA, displays no saturation. The analysis emphasizes the relationship between ground-level observations and upper-air conditions.
- 4.5: Alternative Text Descriptions for Investigation 4
- Detailed alternative text descriptions for this investigation are provided here
Thumbnail: Cumulus Clouds. Cumulus Cloud Panorama by Fir0002 is licensed under CC-BY-NC 3.0.