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San Diego Phenomena

Phenomena in Science Education

Phenomena are the natural and man-made observable events that provide context for the work of scientists and engineers. Recent science standards changed the focus from learning about science to figuring out science. Phenomena are a powerful way to engage students and empower them to wonder and investigate.

Sometimes, we look too hard for the phenomenal events and miss the every-day occurrences that are just as intriguing. The list below is a constant work in progress and will be updated as new submissions are received and new occurrences are observed in and around San Diego County.

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A 20°F Difference Across Mission Bay

Image: NWS San Diego

San Diegans know their city is notorious for its microclimates. The combination of mountains, valleys, canyons and mesas that dot the surface are often responsible for these interesting weather patterns. In the Fall 2019, the National Weather Service (NWS) in San Diego picked up one of the most extreme head-scratching examples of a microclimate: a 20°F temperature difference from one side of Mission Bay to the other.

On October 24, 2019, the NWS recorded 71°F near Mission Blvd. while a monitoring station near Interstate 5 recorded 91°F, two locations less than 3 miles (4.5km) apart.

How could two locations within view of one another have such drastic temperature differences? Is this a location you would expect to find a microclimate? Why or why not?

What questions can we ask to learn more about this phenomenon?

  • What is the average temperature difference of these two locations?
  • How does this October 24 instance differ from the average?
  • This phenomenon occurred during the fall. Did something similar ever happen during one of the other seasons?
  • What was happening over the ocean to the west? What was happening over the mountains to the east?
  • What happens when cold air meets warm air? What is happening weather-wise in the middle of Mission Bay?



WaterNewsNetwork, San Diego’s Six CIMIS Climate Zones

Leonard Perry, University of Vermont: Microclimates: What Do They Mean To You?


NGSS & Grade

3-ESS2-1; 3-ESS2-2, ESS2.D: Weather and Climate

MS-ESS2-5, ESS2.D: Weather and Climate

Carnivorous Plants

Image: Fleet Science Center

Where would you expect to find plants on the food chain?

The Botanical Building in Balboa Park houses many unique species of plants. A selection of those plants goes way beyond simply photosynthesizing. Near the center of the Botanical Building hangs a collection of tropical pitcher plants labeled “Carnivorous,” meaning these are meat-eating plants!

Tropical pitcher plants attract small insects through its pitcher-like trapping mechanism.

  • What caused the pitcher plant to adapt into a carnivorous plant?
  • How does a pitcher plant attract insects?
  • How does a pitcher plant digest its meal?
  • What are the conditions of the tropical pitcher plant’s environment and how do those conditions relate to this plant’s need to eat insects?

Carnivorous plants can also be found in the Bog Garden at the San Diego Zoo. Formulate a list of questions, curiosities and wonders about carnivorous plants and then use the links below to learn more.



San Diego Zoo: Carnivorous Plants

San Diego Zoo: Tropical Pitcher Plants

Zoonooz (SD Zoo): Fantastic Flesh-Eating Plants

CK-12: Carnivorous Plants


NGSS & Grade

K-LS1-1, LS1.C: Organization for Matter and Energy Flow in Organisms

3-LS4-3, LS4.C: Adaptation

4-LS1-1, LS1.A: Structure and Function


Ladybugs Detected on Weather Radar

Image Credit: NWS San Diego

On June 4, 2019, a group of ladybugs (termed a bloom) traveling over Southern California grew so large it was picked up by weather radar at the National Weather Service in San Diego.

At first, the radar echo appeared to be an 80-mile wide band of precipitation. National Weather Service (NWS) staff confirmed it was no traditional cloud, but instead a cloud of ladybugs. The ladybugs were tracked traveling from the San Gabriel Mountains to San Diego County.

What questions do you have about ladybugs and animals that travel in groups? For example:

  • Why do ladybugs behave this way?
  • Why do ladybugs travel in groups?
  • How do that many ladybugs know to move at the same time?
  • Where did the ladybugs come from? Where are they going and why?
  • What can these ladybugs tell us about our environment?
  • What can this movement tell us about animal behavior?

How can we suggest answers to these questions by investigating certain patterns or cause-and-effect relationships related to the environment, seasons and animal behavior?


Twitter: NWS San Diego Original Tweet

LA Times: High-flying ladybug swarm shows up on National Weather Service radar

University of California: Convergent Lady Beetle

University of California: Annual Cycle of Migration

NGSS & Grade

3-LS2-1, LS2.D: Social Interactions and Group Behavior

3-ESS2-1, ESS2.D: Weather and Climate

MS-LS1-4, LS1.B: Growth and Development of Organisms

HS-LS2-8, LS2.D: Social Interactions and Group Behavior

Rex the Lion Balances on One Foot

Image: San Diego Zoo Global

At the entrance to the San Diego Zoo stands a 27-foot (8.25m) 10-ton bronze sculpture of Rex the Lion in mid-leap. The sculpture was designed with only one contact point to the ground, the lion’s front left paw. The other three paws do not contact the ground, which is most evident by the two dramatically flared hind legs.

How does Rex the Lion stand upright and not fall over? Rex uses some clever engineering to accomplish this posture. Before watching the video below to see how Rex stands upright, try to create your own Rex-like structure through a series of experiments on balanced forces.

Need experimentation inspiration? Create a “T” out of two wooden play blocks. Slide the top of the “T” over until the structure fails. How can you redesign the structure to keep it upright? What can you add to make the structure more stable?



YouTube: The Making of Rex, San Diego Zoo

San Diego Zoo: San Diego Zoo Unveils 27-foot Bronze Lion on Front Plaza

Times of San Diego: What an Entrance: Zoo’s 27-Foot Lion Statue, Largest of Its Kind

SD Union-Tribune: Rex the lion returns to San Diego Zoo — in bronze

Dezeen: Cantilevers


NGSS & Grade

3-PS2-1, PS2.A: Forces and Motion

K-2-ETS1-2, ETS1.B: Developing Possible Solutions

3-5-ETS1-3, ETS1.C: Optimizing the Design Solution




Trees Get Most of Their Mass from the Air

Image: Fleet Science Center

The Moreton Bay Fig Tree, located behind the San Diego Natural History Museum in Balboa Park, is one of the largest fig trees in North America. When the tree was last measured in 1996, its crown was 123 feet (37 meters) wide. For comparison, nearly three yellow school buses measuring 45 feet (14 meters) long each could fit underneath end-to-end!

Balboa Park’s Moreton Bay Fig Tree started as a tiny seed more than 100 years ago. Since then, it has gained a tremendous amount of mass.

Where does most of that mass come from? Consider these three statements:

  • Trees get most of their mass from the soil.
  • Trees get most of their mass from the sun.
  • Trees get most of their mass from the air.

How can we plan an investigation to discover which statement is correct?

Many years ago, scientist Jan Baptist van Helmont experimented by watering and weighing a potted tree over time. After five years of tree growth, van Helmont discovered the potted tree weighed significantly more than when his experiment started. What does van Helmont's experiment say about the three options above?  How can additional experiments reveal more about how trees gain mass?

Note: Trees need many resources to grow, however the majority of a tree's dry mass comes from one of the sources above. Dry mass does not include water. The percentage of water in trees varies greatly and that calculation is beyond the scope of this entry.


MSU: Where Do Trees Get Their Mass From?

YouTube: Where Do Trees Get Their Mass From?

BBC: Van Helmont's experiments on plant growth

Balboa Park: Moreton Bay Fig Tree


NGSS & Grade

5-LS1, LS1.C: Organization for Matter and Energy Flow in Organisms


Pineapple Express

Image: NOAA

There are rivers in the sky called atmospheric rivers.

What causes an atmospheric river? Why is this band of moisture confined to a narrow strip, sometimes only a few hundred miles across? How does California’s topography influence an atmospheric river and contribute to rainfall and snowfall in the state?


Image: GOES-West, NASA

Look for the narrow band of clouds originating naer Hawaii (center left). Those clouds, filled with tropical moisture, travel to the coast of California as an atmospheric river. This weather phenomenon is nicknamed the Pineapple Express and is a contributor to the California water cycle. Occasionally, an atmospheric river reaches San Diego.


NOAA: What are atmospheric rivers?

NOAA: Atmospheric river portal

YouTube: GOES-West Satellite Sees Pineapple Express

NGSS & Grade

MS-ESS2, ESS2.C: The Roles of Water in Earth's Surface Processes

MS-ESS2, ESS2.D: Weather and Climate

Pumpkin Patch near Anza-Borrego

Image: ExploreCalifornia.pics

Just outside of Ocotillo Wells, near Anza-Borrego Desert State Park, sits a geologic phenomenon called the Pumpkin Patch due to the rocks’ size, shape and distribution in the field.

How did these rocks form? Why are the rocks a consistent shape and size and how do natural processes continue to expose more of these rocks over the years?

These rocks are a unique geologic feature called concretions, which form when layers of sediment build up around a nucleus like a pebble or a shell. Erosion from wind and water expose these rocks. Similarly, erosion shapes the concretions. Eventually, the same forces that expose the concretions will wear away each of these uniquely shaped rocks.


Desert USA: Concretions

Paleontological Research Institution: Concretions

The Adventure Portal: The Pumpkin Patch

NGSS & Grade:

4-ESS2-1, ESS2.A: Earth Materials and Systems


Great Whites Gather in the Pacific

Image: Tagging of Pacific Predators - TOPP

Trackers on great white sharks in the Pacific reveal that sharks gather in a remote location every year near the mid-point between San Diego and Hawaii.

For years, scientists from Stanford University’s Hopkins Marine Station and the Monterey Bay Aquarium used electronic tags to track the sharks along the California coast. Sharks would feed on seals and sea lions in the coastal waters near San Francisco.  For unknown reasons, the sharks would leave these lucrative feeding ground for a section of ocean roughly the size of Colorado. The sharks would congregate in what was thought to be a food desert. But why? What would cause a shark with a voracious appetite to travel to a random location in the middle of the Pacific dubbed the ‘White Shark Café’?

Why do people move around, and how might those needs be similar to those of the great white? Learn more about the White Shark Café using the links below.


MBARI: Researchers describe abundant marine life at the “White Shark Café”

Schmidt Ocean Institute: Voyage to the White Shark Café

NPR: Great White Sharks Have a Secret ‘Café’ and They Lead Scientists Right To It

LiveScience: Great White Sharks Gather in Droves in the Middle of Nowhere, But Why?

TOPP: Tagging of Pacific Predators 



Pacific coast is colder than Atlantic coast

Image: Google Maps

What does Earth's rotation have to do with ocean temperatures off San Diego? 

The average water temperature off Scripps Pier in September is 66 F. Follow San Diego’s line of latitude (32.7 N) over to Charleston, SC, and you will experience an average water temperature of 82 F. The sun’s rays hit both locations at the same angle, so what other factors contribute to the difference in water temperature?

The quick answer to explain the difference in coastal water temperature is to track the water’s path. Ocean water off San Diego comes from Alaska. Ocean water off Charleston comes from the Caribbean. This explanation opens new questions, like why does water move up the coast on the east but down the coast on the west?

You can explore global ocean circulation through density experiments and through the phenomenon known as the Coriolis effect:

  • Water near the polar regions increase in salinity, and in turn density, because when saltwater freezes it leaves behind salt. This causes denser salty water to sink to the bottom and new water to rush in. This helps explain the circulation in a north-south direction. But why does water travel up one side of a continent and down the other side?
  • As the Earth spins, the Coriolis effect kicks in. As Earth rotates, water at the poles rotates at a slower speed than water near the Equator. This difference in speed causes water to deflect to the right in the northern hemisphere and deflect to the left in the southern hemisphere. The animated photo above is a Coriolos fountain, a visual demonstration of this phenomenon. What direction do you think the spouts of water will go when the fountain is turned? What direction does the water actually go? Why?

Coriolis Fountain. Image: Hector Maciel, YouTube

Need additional visuals to support the Coriolis effect? Use imagery of hurricanes and typhoons in both the Northern and Southern hemispheres. What is similar? What is different? What direction do each spin?


NOAA: Average Water Temperatures, South Carolina and Georgia

NOAA: Average Water Temperatures, Southern California

NOAA: Surface Ocean Currents

NGSS & Grade:

MS-ESS2-6, ESS2.C: The Roles of Water in Earth's Surface Processes