Why is the sky orange? How Google gave people the right info

On the morning of September 10, millions of people in Northern California woke up to an orange sky after wildfire smoke spread like a thick layer across the West Coast. It persisted for days, and it was the first time lots of people had ever seen something like this. 

To understand what was happening, many people turned to Search. According to Google Trends, searches for “why is the sky orange” hit an all-time high this month in the United States. As you can see in the graph below, this wasn't a totally new query. There are many pages on the web with general scientific explanations of what can cause the sky to turn orange. But people wanted to know why, in that moment, where they were, the sky was tangerine tinted.

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Search interest for “why is the sky orange” since 2004, US (Google Trends)

So how does Google respond to a query spike like this? Well,language understanding is at the core of Search, but it’s not just about the words. Critical context, like time and place, also helps us understand what you’re really looking for. This is particularly true for featured snippets, a feature in Search that highlights pages that our systems determine are likely a great match for your search. We’ve made improvements to better understand when fresh or local information -- or both -- is key to delivering relevant results to your search. 

In the case of the orange sky phenomenon, for people in Northern California, the time and location was really important to understanding what these searches were looking for. Our freshness indicators identified a rush of new content was being produced on this topic that was both locally relevant and different from the more evergreen content that existed. This signaled to our systems to ignore most of the specifics that they previously understood about the topic of “orange sky”--like the relation to a sunset--but to retain broad associations like “air” and “ocean” that were still relevant. In a matter of minutes, our systems learned this new pattern and provided fresh featured snippet results for people looking for this locally relevant information in the Bay Area.
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Put simply, instead of surfacing general information on what causes a sunset, when people searched for “why is the sky orange” during this time period, our systems automatically pulled in current, location-based information to help people find the timely results they were searching for. 

Over the course of the week, we saw even more examples of these systems at work. As a residual effect of the wildfires, New York City and Massachusetts started experiencing a hazy sky. But that wasn’t the case in all states. So for a query like “why is it hazy?” local context was similarly important for providing a relevant result.

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For this query, people in New York found an explanation of how the wildfire smoke was caught in a jet stream, which caused the haze to move east. People in Boston would have found a similar feature snippet, but specific to the conditions in that city. And those in Alaska, who were not impacted, would not see these same results. 

These are just two of billions of queries we get each day, and as new searches arise and information in the world changes, we’ll continue to provide fresh, relevant results in these moments.