GLACIERS CLIMATES AND GLOBAL WARMING Glaciers Large masses

GLACIERS, CLIMATES AND GLOBAL WARMING

Glaciers Large masses of ice that form on land for a number of years, more snow falls in winter than melts in summer deform and flow due to their own weight force of gravity strength of ice

Parts in the Mountains

Glacial Budget

Changing Glaciers Stationary Glacier Accumulation = Ablation Receding Glacier Accumulation < Ablation Advancing Glacier Accumulation > Ablation How can you tell?

Measure Them:

Glacier Features End (terminal) moraine Kettle lakes

The Nature of Light is one STRANGE phenomenon! Electric and magnetic forces are really two aspects of the same phenomenon, which we now call electromagnetism Light exhibits BOTH wave-like (wavelength) AND particlelike (photon) natures

The Electromagnetic Spectrum

An opaque object emits electromagnetic radiation according to its temperature (example in VIS) u Hot objects emit more radiation per unit surface area than cold objects

u Hot objects emit shorter wavelength (higher energy) photons than cold objects Example in IR (That’s Not Me!)

Atmospheric Pressure: a measure of the weight of overlying molecules of air PSI mm. Hg or in. Hg Bar Gravity pulls the molecules toward Earth

Temperature Variations II Can I ask a simple question? If Hot Air rises, why is there snow in the mountains? Answer is not so simple! How is each layer heated? It needs: Heat Source, which emits some… Type of Radiation Substance that absorbs a particular set of photons. Good Absorbers make Good Emitters – BUT Not all materials are GOOD absorbers – some are SELECTIVE absorbers!

The Solar Curve

The Thermosphere Temperature rises with increasing altitude Energetic rays of the Sun are absorbed by ions of O and N Highest temperature of any layer is reached - more than 1000°C!! Pressure is VERY low - very few atoms or molecules around Thermosphere grades out into the vacuum of space.

The Mesosphere Temperature drops with increasing altitude “Heat source” is hot material (atoms) escaping from the Stratosphere Ozone doesn’t exist in this thin air Sun’s rays are extremely energetic, but there is nothing there to absorb the energy! Top of Mesosphere is the Mesopause.

The Stratosphere Temperature rises with increasing altitude The SUN must be the heat source! OZONE absorbs UV rays and becomes warmer “Heat Rises”, but. . . . what this really means is that “Air that is warmer than its surroundings will rise” Air doesn’t rise much in Stratosphere - lack of vertical motion results in layering Top of Stratosphere is called the Stratopause.

The Troposphere This is also known as the “Weather Sphere” Temperature drops with increasing altitude Rate of decrease with altitude is known as the Environmental Lapse Rate (ELR) Average (or Normal) ELR is around 6. 5°C/km (3. 5°F/1000 ft), but varies widely with place, season, etc. Earth is the source of heat for the Troposphere Discussed further in a moment Top is defined where the temperature stops dropping - called the Tropopause.

Troposphere: Where the Weather Happens Temperature DROPS with altitude Abundance of Greenhouse Gases Could this be heated by the Sun? Gamma, X-rays absorbed in Thermosphere UV absorbed in Stratosphere VIS passes through it all! How do we know that?

Albedo Reflectivity of surface Fresh snow: Asphalt: Green Forest:

Greenhouse Gases H 2 O absorbs ~ 5 X more microwaves than all other GHGs combined!! Can we control its abundance in the atmosphere? CO 2 – stable in our atmosphere Now at about 400 ppm (0. 040%) Can we control its abundance in the atmosphere? CH 4 (Methane) Very strong absorber at Breaks down to H 2 O and CO 2

Absorption Spectra

Greenhouse Effect

Analogy Think of GHGs as baseball mitts… Are mitts being added?

Water Vapor in the Air Increase in CO 2 Vapor Saturation Curve 50 Increase the 45 Temperature Increase the Temperature Increase the H 2 O 35 g vapor / kg air 40 30 25 20 15 Increase the 10 Temperature 5 Repeat… 0 -40 -40 -35 -35 -30 -30 -25 -25 -20 -20 -15 -15 -10 -5 -5 00 55 10 10 15 15 20 20 25 25 30 30 35 35 40 40 Series 1 0. 3 0. 75 2 3. 5 5 7 10 14 20 26. 5 35 47

Adding Mitts? Popclock: http: //opr. princeton. edu/popclock/

Predictions of Climate Change Globally, average surface temperatures will increase Globally, average precipitation will increase, but its distribution is uncertain Northern hemisphere ice will decrease, southern hemisphere ice may increase Arctic land areas will experience wintertime warming Sea level will rise at an increasing rate with drowning of lowlevel coastal plains Decreasing soil moisture in the northern hemisphere may make farming nearly impossible in much of North America and Europe Plants and animal ranges will expand in some cases, shrink or disappear altogether in others