Transcript Metro Lecture 5-7

Dan Staley
Meteorology and Trees
May 7, 2008
Agenda
• Introduction
– “The Basics” of weather
• Severe Weather
–
–
–
–
Wind
Tornadic activity
Thunder, lightning
Flash floods
• Relationships to trees
Introduction
• The Basics:
– Scale – very important in nature
• Space (spatial)
– Relative lengths, areas, distances
and sizes
– [Mega-] global
[Macro-] continental, regional
[Meso-] regional, local
[Micro-] yard, flowerpot
Introduction
• The Basics:
– Scale
• Time (temporal)
– Relative duration
– [Macro-] epoch, era
[Meso-] century, decade
[Micro-] minute, second
Introduction
• The Basics: Air & its movement
– Hot -> Cold
– High -> Low
conduction
advection
• High pressure = fair weather
–
–
–
–
Warm air rises = less dense
Cool air sinks = more dense
Sinking air compresses and warms
Land heats and cools faster than
water
Hot -> Cold: Global
• Earth’s axis and sunlight
Hot -> Cold
• Earth’s axis and sunlight
Hot -> Cold
• Resultant average temperatures
Hot -> Cold
• Predictable pattern – 3 cell
Hot -> Cold
• Predictable pattern
Predictable Pattern
• Winds
Hot -> Cold
• Predictable pattern
Wind and Weather
•
Infrared photo
Water vapor photo
Wind and Weather
•
Infrared photo
Water vapor photo
Wind, Weather Patterns
•
Wind, Weather Patterns
Wind, Weather Patterns: January
Wind, Weather Patterns: July
Hot -> Cold: Regional & Local
• Valley winds: up in day, down at night
Hot -> Cold: Regional & Local
High-> Low: Regional & Local
• Trees: flagging - alone
High-> Low: Regional & Local
• Trees in forests tend to live longer than
lone trees (open grown)
Hot -> Cold: Regional & Local
• Humanity has used hot -> cold for many
centuries
Hot -> Cold: Regional & Local
• Humanity has used hot -> cold for many
centuries
High -> Low: Weather Maps
High -> Low: Weather Fronts
• Fronts are the boundaries between
different air masses
High -> Low: Weather Fronts
• Reminders:
– Warm air rises
– Rising air cools, condenses, forms clouds
• Rapid rise, taller clouds, severe weather
potential
– Cold air more dense
– Air flows into low pressure (counterclockwise
in northern hemisphere)
High -> Low: Weather Fronts
• Cross-section of a cold front
High -> Low: Weather Fronts
• Cross-section of a warm front
High -> Low: Weather Fronts
• A cold and warm front section
High -> Low: Weather Fronts
• Most summertime severe weather comes
from the clash of cold front and warm, moist
air
High -> Low: Weather Fronts
• Most wintertime severe weather comes
from trying to move cold, dense air
Severe Weather: Wind
•
• Wind is air
trying to equalize
pressure - from
high to low &
“falling downhill”
into low pressure
Severe Weather: Wind
•
Severe Weather: Wind
• Isobars are like topographic
lines on a map
Severe Weather: Other Wind
• Chinook, foehn
Severe Weather: Other Wind
• Chinook, foehn
Severe Weather: Other Wind
• Microburst
Severe Weather: Other Wind
• Tornado
Severe Weather: Other Wind
• Tornado formation
Severe Weather: Other Wind
• Tornado formation
Severe Weather: Lightning
• Why does lightning form?
Severe Weather: Lightning
• Why does lightning form?
Severe Weather: Lightning
Severe Weather: Flash Flood
•
•
•
•
Time scale: hours
Caused by intense thunderstorms
Especially in desert southwest
Never drive into water across roads
Severe Weather: Flash Flood
• In US, more people die from floods than
from hurricanes, tornadoes, lightning on
average each year
Severe Weather: Hurricane
• Hurricanes are a method of transporting
heat from equatorial regions to the poles
(hot to cold) via the energy in water vapor
Severe Weather: Hurricane
• Causes of hurricane damage:
– Tidal surge
Severe Weather: Hurricane
• Causes of hurricane damage:
– Wind
Severe Weather: Hurricane
• Causes of hurricane damage:
– Tornadoes
Trees
• Trees moderate wind
Trees
• Trees moderate wind
Trees
• Trees moderate sunlight – energy savings
Trees
• Trees moderate sunlight – pavement
savings
– Protection from sunburn on sidewalk
Trees
• Trees moderate sunlight – pavement &
parking lots
– Protection from gasoline vaporizing in heat
Trees
• Trees are preferred by people in both
residential and commercial areas:
“nearby nature”
Trees
• We are beginning to understand that
greenery helps us heal – “attention
restoration” and “nearby nature”
– Greenery outside a window speeds recovery
Wrap-up
• “Savanna hypothesis” – people prefer trees
and open areas
• Trees are not found everywhere – there
must be enough water and not too
much wind
• People are generally found where trees are
found – weather patterns
Wrap-up: Meteorology
• Air & its movement
– Hot -> Cold conduction
– High -> Low advection
• High pressure = fair weather
–
–
–
–
Warm air rises = less dense
Cool air sinks = more dense
Sinking air compresses and warms
Land heats and cools faster than
water
Wrap-up: Meteorology
Thank you!