From NASA's Earth Science Enterprise 2002 Summer Workshop

Table of Contents

Topics - First Session, Part I

Radiation

• Basic Terminology
• Solar and Terrestrial
• Weather Radar
• Satellite Images
• Global Balance vs Temperature

Winds

The General Circulation of the Atmosphere: Tropical Emphasis

• El Niño
• Hurricanes

Exercise: Hurricane Frequency in the Atlantic and Eastern Pacific Basins

Topics - First Session, Part II

Global Warming - The Enhanced Greenhouse Effect

Land Use - The Urban Heat Island

Exercise: Temperature Trends

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Topics - Second Session

Basic Air Pollution Meteorology

Sound Propagation in the Lower Atmosphere

Radiation: Basic Terminology

• Radiation is not "bad" and is essential for life as we know it
• Defined: energy radiated in the form of waves or particles (molecular motion)
• Absorption / Reflection (Albedo)
• The Electromagnetic Spectrum
- shorter wavelength = more energy
- every object emits some radiation at all wavelengths, but there is a peak wavelength where it emits the most
• Emission Spectra of Sun vs Earth
- higher temperature (avg. K.E. of the molecules of an object)
... greater energy emitted
... shorter wavelength of peak emission
• Atmospheric Constituent Absorption Spectra
• Intensity

Radiation: Weather Radar and Satellite Images

• Weather Radar (Non-Doppler)
- an instrument that emits (transmits) radiation at a pre-selected wavelength
... select wavelength based upon size of target (small target, small wavelength)
... a receiver on the radar can detect the amount of radiation reflected back
... Intensity (of rain, for instance): more reflected = heavier rain
... Distance: emit radiation in pulses and time its return [D=(V*T)/2]
• Satellite Images
- Visible
... detector on satellite senses reflected solar radiation in the visible range
... good for determining cloud texture (convection)
... not useful at night
... atmosphere is transparent to visible radiation (poorly absorbed)
- IR
... senses terrestrial radiation that escapes through atmospheric window
... color coded or gray scaled
... useful day and night
... can determine cloud height based upon amount of emitted radiation
- Water Vapor
... senses radiation emitted by water vapor (high-level)
... useful for determining atmospheric motion when no clouds present

Visible                              Infrared

Water Vapor

Colorized Infrared Image                              Composite Radar Image

Radiation: Global Balance vs Temperature

• Net heating or cooling
- Cooling occurs when an object emits more radiation than it absorbs
- Heating occurs when more radiation is absorbed than is emitted
• Surface Radiation Budget: The Sun Heats the Ground, the Ground Heats the Air!

• Global Radiation Balance and Tilt of Earth's Axis

• Global Temperature: (GLOBE program, 1987 data, January / July)

Winds

• Pressure Gradient Force (Horizontal)
- sets air in motion, from high to low pressure
• Coriolis Effect
- deflects flow to the right in northern hemisphere
- balances P.G.F. in absence of friction
• Friction
- slows speed and tempers deflection

The General Circulation of the Atmosphere

• Global Air Flow

The General Circulation: The Hurricane

• Birth Regions / Frequency

• Structure

• Storm Surge- the leading cause of death

Lab Exercise 1: El Niño and Hurricane Frequency

• Hurricane Frequency Data

• El Niño and La Niña Years

• Procedure (use a spreadsheet program)