Wildfires are not hot enough to melt glass, yet images of Maui show burnt out cars with no windows.
The heat from a car when it’s on fire may cause the windows to break, but there are examples of car windows melting in the heat of a fire. Wildfires can reach temperatures in the range at which glass can melt.
We’ve seen a number of social media posts claiming that photos of the aftermath of the wildfires on Maui somehow prove that the fires were actually caused by directed energy weapons.
One post on Twitter (now known as X) showing a picture of burnt out cars on a road in Lahaina, Maui, says: “All the glass in the cars is gone, melted OUT. Glass melts at above 2700 degrees F or higher. Wild fires are more than a 1000 degrees COOLER than that. Go look at the pics yourself. DEW it. [sic]”
That post has also been shared on Facebook.
But the pictures of burnt-out cars with no windows in the aftermath of fires does not mean weapons were involved. There are examples of glass melting during a fire, and it is also possible the glass shattered due to the heat.
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‘DEW’ appears to be a reference to directed energy weapons—systems that emit laser or radio frequency energy in order to cause disruptive, damaging or destructive effects on equipment or facilities, such as deterring people from an area or damaging drones. There is no evidence these weapons caused the fires in Hawaii.
Other baseless claims about these weapons have gone viral recently following the disaster in Maui and we have checked other posts claiming they caused the fires. We’ve also checked posts falsely claiming the fires weren’t hot enough to melt the aluminium in car wheels.
According to the US Department of Agriculture, forest fires specifically often “reach or exceed temperatures of 2,000° Fahrenheit” (1,100°C). Less extreme fires on the forest floor would be slightly cooler, at 800°C. The exact temperature depends on factors such as fuel source and oxygen levels.
Glass softens over a wide temperature range, rather than melting sharply at a specific temperature. It’s true that glass does melt within the 2500°F to 2900°F range (1400°C to 1600°C) as one of the Facebook posts claims, but that doesn’t mean it’s impossible for the temperatures of a wildfire to melt it in some cases.
It is possible for the glass in the windows of the cars pictured to melt if the car is set alight, as pictures of fire-damaged cars elsewhere show. A photo was also taken of melted glass bottles in the back of a burnt out truck following the Maui wildfires.
High heat from fires can also shatter car windows. Radiant heat from wildfires can also melt or shatter glass in windows of homes.
Another Facebook post showing an image taken in Lahaina, of burnt out cars with singed palm trees in the background says: “Glass windows melt at 2552-2912 fahrenheit, trees burn at 750-1050 fahrenheit. All glass gone, but trees remain”.
Erica C. Fischer, assistant professor in the School of Civil and Construction Engineering in the College of Engineering at Oregon State University told Full Fact: “The damage that we see in Maui is not unusual.
“During a fire within the wildland urban interface (WUI), embers—or pieces of combustible material that are on fire—are transported large distances due to high winds.
She added: “These embers will ignite large objects, such as houses, because they land on roofs, porches, decks, etc. There is a lot of surface area on a house for them to land and ignite.
“It is common to see partially burned trees or trees that are not burned at all. However, homes, once ignited will burn for several hours creating embers that can ignite other portions of the community.
“It is not uncommon to see burned down homes and cars while also seeing trees and utility poles virtually undamaged.”
So the fact that trees remain standing while surrounding objects or homes have been burnt does not prove the damage wasn’t caused by wildfire.
Image courtesy of State Farm
Correction 1 September 2023
A previous version incorrectly referred to glass burning in the conclusion. We have changed this to melting.
This article is part of our work fact checking potentially false pictures, videos and stories on Facebook. You can read more about this—and find out how to report Facebook content—here. For the purposes of that scheme, we’ve rated this claim as partly false because although glass has a high melting point, fire can cause car windows to melt but in many cases the heat can also cause them to break.
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