Exceptional heat and humidity made for an electric atmosphere in the Washington region Wednesday evening.
Daytime temperatures that surged into the mid-90s combined with oppressive mugginess to turn the air into a steamy soup that fueled a vigorous and explosive line of storms.
In addition to torrential rain and violent bursts of wind, the intense storms unleashed frequent cloud-to-ground lightning — some of it quite dramatic. In Kensington, Md., the backyard camera of resident Trevor Riley captured the shocking moment one of those lightning bolts struck a tree and the resulting video is a sight to see.
As the lightning intercepts the tree, there’s a blinding flash of yellow light, a deafening crash of thunder and its bark explodes. But there is a lot more to it.
If you watch the video closely, you’ll notice a couple of pieces of bark flying before the main “explosion” looks to take place. That could be for myriad reasons.
While the quality and length of the video make it difficult to know for sure, one possibility is that it is an early “upward streamer.” That’s a tiny bolt of electricity that reaches from the ground a few yards or so up toward the clouds, as if to say, “Pick me!” A dozen or so of these may precede any lightning strike. Only one is met by a downward-propagating “stepped leader.” When the two channels meet, a massive current of electricity flows along the path — like an onrush of traffic once two highways are connected. The lightning bolt may “pulse” with current, throbbing like a bruise, as it empties its charging imbalance in a series of punctuated bursts. That explains why lightning flickers.
In this case, it looks as though the tree was struck by two distinct pulses of current. Notice the shadow beneath the hanging ornament is a bit to the left or directly beneath it once the video begins. It’s probable that a first, slightly lesser pulse of energy originated from the right side of the top of the tree.
Then it becomes clear that the main strike occurs. It’s actually possible to watch the source of light change acutely by watching the shadow beneath the hanging ornament appear in three or four subtly different locations — first right and closest to the camera before returning to directly beneath the ornaments — when played frame by frame. This is because the light source — the “leader head,” or tip of the main downward streamer racing down from above — is moving. Lightning jumps in 50-yard segments and is shooting down from the sky at a quarter-million miles per hour. The lightning blinds the camera as the main discharge occurs.
This main discharge brought current all the way to the ground. After the camera recovers from being blinded, one can notice a strip of fire-like plasma on both sides of the tree, especially the right. It’s likely that one is the main lightning strike “decaying” into short-lived glowing puffs of plasma. The other area of fire may be that or the vaporization of sap/fluids inside the tree trunk.
The strike in Kensington was just one of several in the region Wednesday evening.
Another lightning bolt struck a massive tree in northwest Washington’s American University Park neighborhood, splitting it apart and taking down power lines.
In Loudoun County, Va., a lightning strike set a house ablaze.
In addition to all these lightning strikes, damaging winds took down scores of trees around the region, with the greatest concentration to the north and northwest of downtown Washington, especially near the Interstate 270 corridor.
The storms resulted in tens of thousands of customers without power in Northern Virginia, the District and Maryland.