Observing Clouds andContrails for GLOBE and

NASA

Dr. Lin ChambersNASA Langley Research Center

Hampton,VA

Our Objectives

• Obtain contrail and other cloudinformation from the largest possiblenetwork of ground observers

• Use to:– Validate satellite retrieval algorithms– Improve contrail prediction methods

Outline

• What are contrails?• Why is NASA involved?• Why and how are students important to

this study?

Outline

• What are contrails?• Why is NASA involved?• Why and how are students important to

this study?

What are Contrails?• Contrails are

CLOUDS that formin the wake ofaircraft.

• Contrail is ashortened name forcondensation trails.

• Also known as vaportrails, jet trails,“chemtrails”

Contrails have been aroundfor a long time!

• They were firstdescribed in thescientific literature in1919.

• During WWII,contrails sometimeslittered the skiesduring aerialcombat.

What is a Mixing Cloud?

The cloud that formson your breath duringa cold day is a mixing

cloud

B. Cold, dry air inupper atmosphere

A. Hot, moistair from planeexhaustC. If you cross

the line …contrail!

Do Contrails Affect Cloud Cover?

Outline

• What are contrails?• Why is NASA involved?• Why and how are students important to

this study?

Global Cloud CoverAugust 26, 1993

EARTH'S ENERGY BUDGET

Incoming

solar energy

100%

Reflected by

atmosphere

6%

Reflected

by clouds

20%

Reflected from

earth's surface

4%

Absorbed by

atmosphere 16%

Conduction and

rising air 7%

Absorbed by

clouds 3%

Radiated to space

from clouds and

atmosphere

64% 6%

Radiated

directly

to space

from earth

Carried to clouds

and atmophere by

latent heat in

water vapor 23%

Radiation

absorbed by

atmosphere

15%

Absorbed by land

and oceans 51%

Derived Product

Requires CloudDetection andCloud PropertyRetrieval

When the upperatmosphere ismoist enough,the contrailscontinue to grow.

Under theseconditions, thecontrails becomepersistent.

Why Do We Study Contrails?

We currentlyestimate thatcontrails addan additional0.5 to 5 %warming tothegreenhousegas effect.

Persistentcontrailsoccasionallycover largeareas.Like cirrusclouds,contrailslikelycontribute toglobalwarming.

Air traffic and persistent contrail coveragewill continue to increase.

By 2050, warming due to contrails may be 2.5to 25 % of the current greenhouse gas warming.

Outline

• What are contrails?• Why is NASA involved?• Why and how are students important

to this study?

Our estimates ofthe climaticeffects ofpersistentcontrails are stilluncertain.We still havetrouble estimatingcontrail coverage.

Why can students help?

Most contrails are still smaller than the resolutionof most satellites.

Why can students help?

Data Sheet

Initial GLOBEContrail Data

AnalysisDr. Dave Duda,

Hampton University

Method•Compare GLOBE obs to:

• RUC (Rapid Update Cycle;Benjamin et al.)• ARPS (Advanced RegionalPrediction System; Xue et al.)

• Initial comparison for April 2004• 1500 GLOBE observations ofcontrails

Website & Activities

http://asd-www.larc.nasa.gov/GLOBE/

• Some other things you may see…

Inverse contrails (distrails)

Aircraft sometimes make holes in clouds!

Contrail Cousins

Cloud “zippers” on Father’s Day, 2004