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Why San Francisco Is Foggy

Interactive passage with audio narration, comprehension questions, and printable PDF.

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Format: Interactive (Online), Printable (PDF)
Grades: 5678
Subjects: scienceela
Standards: MS-ESS2-5
Languages: English, Spanish

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What's included

Reading passage

Reading comprehension

Audio narration

With word word highlighting

Comprehension quiz

Auto-graded

Writing activity

Open-ended response

Glossary & flashcards

Vocabulary practice

Differentiated version

Adapted for varied levels

Spanish translation

Bilingual support

About this reader

This engaging 400-500 word science reading passage explores why San Francisco experiences its famous fog phenomenon, nicknamed Karl. Aligned with NGSS standards MS-ESS2-5 and MS-ESS2.C, the passage explains how warm Pacific air drifts over the cold California Current, creating a temperature contrast that condenses moisture into fog. Students learn about the role of ocean currents, air temperature, and condensation in weather patterns. The passage includes real-world connections to San Francisco's unique climate, coastal redwood ecosystems, and local culture. Audio-integrated content supports diverse learners with vocabulary development featuring 8-10 key science terms. Activities include multiple-choice comprehension questions, writing prompts, and graphic organizers that help students analyze cause-and-effect relationships in Earth systems. Perfect for grades 6-8 students studying weather, climate, and ocean-atmosphere interactions.

Written by Workybooks TeamPublished by Workybooks

Sample passage and quiz content

CONTENT PREVIEW

Golden Gate Bridge emerging from fog with hills in the background, capturing a moody San Francisco scene. — "Golden Gate Bridge emerging from fog with hills in the background by Stephen Leonardi / Pexels.

San Francisco's famous fog forms because of a unique interaction between warm air and cold ocean water. When warm Pacific air drifts eastward toward California, it passes over the California Current. This ocean current carries cold water from the north along the California coast. The warm air cools rapidly as it moves over the frigid water. Cold air cannot hold as much water vapor as warm air can. The cooling causes condensation, which means water vapor changes into tiny liquid droplets. These millions of droplets cluster together and form fog.

Scientists explain that this process creates a type of fog called advection fog. The temperature gradient between the warm air and cold water must be significant for fog to develop. Evidence shows that the California Current maintains temperatures around 50 to 55 degrees Fahrenheit year-round. Meanwhile, summer air temperatures over the Pacific Ocean can reach 70 degrees or higher. This contrast of at least 15 degrees creates ideal conditions for fog formation. The fog then drifts inland through gaps in the coastal mountains, with the Golden Gate serving as a natural pathway into the bay.

The fog has real effects on San Francisco's climate and ecosystems. Summer temperatures in the city rarely exceed 70 degrees because the fog acts like a natural air conditioner. Coastal redwood trees depend on fog for survival during dry summers. The trees capture moisture directly from fog through their needles, a process called fog drip. Scientists observe that fog can provide up to 40 percent of the water these ancient trees need. The fog also influences local culture, creating the gray, cool conditions known as June Gloom.

Understanding San Francisco's fog matters because it demonstrates how ocean currents shape regional weather patterns. The interaction between air temperature, water temperature, and condensation shows how Earth's systems connect. Climate scientists study this fog to understand how changing ocean temperatures may affect coastal climates in the future. The fog serves as a visible example of the water cycle in action and reminds us that weather results from complex interactions between the atmosphere and oceans.

Interesting Fact: San Francisco residents nicknamed the fog "Karl" through social media, and the fog now has its own Twitter account with thousands of followers who track its daily movements across the city.

What causes San Francisco's fog to form?

Warm Pacific air cooling over the cold California CurrentRain clouds moving in from the mountainsCold air warming over hot ocean waterPollution from the city mixing with ocean air

What is condensation?

Water changing from liquid to gasWater vapor changing into liquid dropletsIce melting into waterClouds forming in the upper atmosphere

According to the passage, what temperature does the California Current maintain year-round?

Around 70 to 75 degrees FahrenheitAround 60 to 65 degrees FahrenheitAround 50 to 55 degrees FahrenheitAround 40 to 45 degrees Fahrenheit

What does the term 'temperature gradient' mean in the passage?

The speed at which air movesThe amount of water in the airThe difference in temperature between warm air and cold waterThe height of fog above the ground

How does fog help coastal redwood trees?

It provides shade from the sunIt provides up to 40 percent of the water they need through fog dripIt keeps insects away from the treesIt helps the trees grow taller

Based on the passage, why do summer temperatures in San Francisco rarely exceed 70 degrees?

The city is located in the mountainsStrong winds blow through the cityThe fog acts like natural air conditioningThe ocean water is too warm

What can scientists learn by studying San Francisco's fog?

How to predict earthquakesHow changing ocean temperatures may affect coastal climatesHow to build better bridgesHow to make artificial fog

Why does the Golden Gate serve as a pathway for fog into the bay?

It is the warmest area along the coastIt is a natural gap in the coastal mountainsIt has the strongest winds in CaliforniaIt is where the ocean is deepest

True or False: Cold air can hold more water vapor than warm air.

TrueFalse

True or False: San Francisco residents nicknamed the fog 'Karl' through social media.

TrueFalse