The Atmosphere

Lab #11

INTRODUCTION TO EARTH SCIENCE

Dr. Gregg Wilkerson and Jack Pierce

The Atmosphere

Lab #11

Atmospheric Objectives:

• Students will learn how the Earth’s atmosphere is structured

by observing its layers, temperature variations, and

distribution of atmospheric pressure.

• Students will learn how air parcels circulate within the

Earth’s atmosphere, creating wind

• Students will understand the nature of insolation entering

the Earth’s atmosphere, specifically the impact of ultraviolet

radiation on various types of material.

• Students will gain insight regarding the global warming

debate.

T

T

T

T

Troposphere

• 11 km thick (7 miles)

• 80% of the atmospheric

weight

• All storm activity takes

place

• environmental lapse rate

6.50C/1000 m

Stratosphere

• 11 km – 50 km (7-31 miles)

• 20% of the atmospheric

weight

• Contains the ozone layer

(lower stratosphere)

• Temperatures increase with

altitude

Mesosphere• 50-80 km (31-50 miles)

• atmosphere thins rapidly

• coldest layer → - 900C

Thermosphere• Begins at 80 km (50 miles)

• Temperatures as high as

12000C

Atmospheric Pressure

• Force/unit area exerted against

a surface

• Represents the weight of the

atmosphere

• Uniformly decreases with altitude

• However --NOT uniform

across the entire earth

• Analogous to boiling water

High

Pressure

14.7 psi (1013 mb)

Low

Pressure

De

cre

as

ing

Pre

ss

ure

Thinning Air

Molecules

Air masses rise and

fall within the

atmosphere.

Dependant on the

cooling/heating of

the Earth’s surface

Cooling air sinking air High Pressure

Warming air rising air Low Pressure

What causes high and low pressure zones ??

High Pressure• Cold sinking air

Low Pressure• Warm rising air

Anticyclone Cyclone

Wind - What is it?• Unbalanced air pressures• High air pressure moves into low

pressure systems

Low Pressure

High Pressure

Cooling descending

air parcel

Rising ascending

air parcel

High pressure air rushes

to fill the “void” left by rising

the rising air parcelWarm

Land Cooler

Water

Isobars – equal points of pressure

isobar

Pressure Gradient Force

• primary force that causes wind

• always drawn perpendicular to isobar lines.

Producing an

Isobar map

Light is a form of electromagnetic radiation, vibrating electric and

magnetic fields moving through space.

What is light?

(insolation)

Insolation (light from the sun) is measured using wavelength

wavelength

What is incoming solar radiation? (insolation)• energy the earth receives from the sun

• travels 300,000 km/sec (186,000 mi/sec)

• travels in “wave motion”

• Sun rays comprise the electromagnetic spectrum.

Electromagnetic Spectrum (EM scale)

Wavelengths the human eye can see

R O Y G B I V

Not harmful Very harmful

Long Waves Short Waves

Visible light spectrum

passing through a glass

prism

Visible light spectrum

Is separated into the various

ROYGBIV wavelengths

Glass Prism

Thermosphere

Mesosphere

Stratosphere

Troposphere

most short waves

are absorbed

UV waves are absorbed

and make ozone (O3)

Most EM is longwave

before hitting the surface

(visible and IR)

OZONE

insolation

97% of UV radiation absorbed

3% of UV radiation makes to

the Earth’s surface.

UV

Today’s Lab– take a deep breath

• Complete part A• definitions – definitions can be found in the

lab text –READ IT

• Complete part B• Complete the diagram by illustrating the layers of the

atmosphere – use colored pencils

• Complete the US isobar map (USE PENCIL!

• Complete part C• Acquire the UV detecting beads and follow the instructions

outlined in part C

• Complete part D• Read the lab text and answer questions regarding

the greenhouse effect and the relation to global warming.