California Wildfires. What causes fires to spread?

California Wildfires

What causes fires to spread?

So. California Is Mountainous

Hot air rises, fanning flames on mountain

slopes..

High Winds Blow East to West

Effect of Santa Ana Winds

NASA photo shows smoke plume over Pacific caused by powerful Santa Ana winds in So Cal

The winds fanned the fires and caused their rapid spread

NASA photo shows smoke plume over Pacific caused by powerful Santa Ana winds in So Cal

The winds fanned the fires and caused their rapid spread

What causes Santa Ana winds?

High pressure area over the Great Basin

Low pressure area over the Pacific

Air from the high flows to the low

The greater the difference between the high and the low, the stronger the winds

High pressure area over the Great Basin

Low pressure area over the Pacific

Air from the high flows to the low

The greater the difference between the high and the low, the stronger the winds

Another Santa Ana Effect…

As the high-altitude winds from the Great Basin sweep down the mountain slopes and descend to sea level,

they warm up and dry out because of the increase in air pressure at that altitude.

That's what makes the Santa Ana winds so withering.

As the high-altitude winds from the Great Basin sweep down the mountain slopes and descend to sea level,

they warm up and dry out because of the increase in air pressure at that altitude.

That's what makes the Santa Ana winds so withering.

What Causes Increased Hazard?

A wet season, followed by dry season

Brush fires are fiercest when there is lots of dried brush for fuel

A wet spring tends to increase the fire hazard

If a dry autumn follows, that leaves lots of dried brush, ready to burn

A wet season, followed by dry season

Brush fires are fiercest when there is lots of dried brush for fuel

A wet spring tends to increase the fire hazard

If a dry autumn follows, that leaves lots of dried brush, ready to burn

Human Life Choices

Original people who lived in Los Angeles area, the Tongvas, called San Fernando Valley the “Valley of the Smokes.”

To live successfully near the mountains, Californians must learn to exercise awareness of the natural environment.

Original people who lived in Los Angeles area, the Tongvas, called San Fernando Valley the “Valley of the Smokes.”

To live successfully near the mountains, Californians must learn to exercise awareness of the natural environment.