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Weather of the San Francisco Bay Area
Bay Model 3D map: important concepts
Prevailing westerly winds are deflected to the right by coriolis effacts due to the rotation of the earth.
These winds blow water away from the coast, cold deeper waters rise (upwelling) to replace the displaced water.
Winds pick up water vapor from the ocean then blow over colder water where water drops condense forming fog.
Sun warms the central valley causing upward convection.
Air moves from the ocean toward the central valley bringing fog inland through gaps in coastal topography.
Microclimates in San Francisco an Exploratorium Video http://www.exploratorium.edu/tv/index.php?project=104&program=1168&type=clip
Cloud drop formation:
Air temperature drops below the dew point with cloud condensation nuclei present this is well illustrated by the cloud in a bottle Snack. In the snack there is a pressure reduction resulting in cooling.
Cloud in a bottle (Exploratorium snack) http://www.exploratorium.edu/snacks/fog_chamber/index.html
Cloud production by cooling.(NOAA activity) http://www.prh.noaa.gov/hnl/kids/activities.php#Cloud v
This activity also has a second part showing convection using ice and hot water.
Dew Point (UCDavis) Measure the dew point by cooling a can with ice until droplets form on the outside.
http://ists.pls.uni.edu/biomes-geomes/biomes_geomes_act/geomes/PDF/dewgetpoint.pdf
http://biomet.ucdavis.edu/frostprotection/Measure%20Dewpoint/fp003.html
Cloud Condensation Nuclei http://apollo.lsc.vsc.edu/classes/met130/notes/chapter5/ccn.html
Coriolis model NOAA http://oceanservice.noaa.gov/education/lessons/twisting_air_lesson.html
Convection Currents
This model demonstrates convection currents in water, which we can generalize to understand the movement of water vapor in our atmosphere as part of the water cycle. Try this adaptation to really drive the convection: Support your plastic box with two coffee mugs – one filled with hot water, and the other one empty. Add the red food coloring to the hot water side of the box. http://eo.ucar.edu/educators/ClimateDiscovery/ESS.htm
Exploring the Exploratorium at the Piers
Look at temperatures of objects in the city using a far infrared thermal camera.
Measure an urban heat island using an infrared thermometer NESTA, infrared thermometers cost about $30 in 2011 from amazon.
http://www.windows2universe.org/teacher_resources/teach_heat.html
Look at the world in the near infrared using acrylite 1146 acrylic filters. (Little Shop of Physics) http://littleshop.physics.colostate.edu/NSTA2010Documents/SeeBeyondTheRainbow.pdf
Solar Motion record the path of the sun across the sky.
http://lawrencehallofscience.org/pass/passv12/PASSv12SolarMotionDemo.pdf
Observe cloud motion in a mirror using a nephoscope.
Build a nephoscope
Cloud drop growth model
The aggregation of raindrops and ice crystals can be modelled by floating aluminum circles or squares on the surfacetension of water. They seem to attract as they fallinto each others depressions assembling into clusters. Clusters of two coins are easily disrupted by slight vibration. Larger clusters require larger vibration to disprupt. This is why cloud condensation nuclei speed up the formation of water drops, the hydrophillic nuclei attract water molecules and bind them in place.
Build a thermometer by Eric Muller http://www.exo.net/~emuller/activities/Canned%20Heat.pdf
Measuring Raindrops a NASA lesson. (Allow rain to fall onto a 1/4 inch thick layer of flour, or to hit light colored card stock.)
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Scientific Explorations with Paul Doherty |
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1 April 2011 |