Key words: albedo, refraction, reflection, black body, grey body, latent heat, radiation, conduction, convection

The goal of these lectures will be to try and understand global change.

We know that is involves energy. What is key is not just knowing the sources of energy but also the processes by which energy is used.

For example, What are some processes of drinking?
-sipping, chugging, gulping swallowing

Although these are examples of drinking they are all quite different processes from one another.

Playing with the Power of Water

We would like to understand the change of matter through its 3 stages, solid, liquid and gas.

1. Water is unique in that it can exist in these three states.
2. To reach any of these states, water either takes or gives off energy.
3. There are six processes that water can under go.

In knowing these six processes, it is important to determine if each process is storing or giving off heat.

When adding or subtracting heat, one is referring to latent heat. Latent heat is hidden heat.

What changes does water undergo when it is in its various stages? For example, How much of an iceberg (solid water) shows in a body of water (liquid water)? Approximately 1/10 of the entire iceberg is visible. This indicates that the solid form of water is less dense than liquid water.

An example of sublimation is freezer burn. Sublimation is the conversion of a solid to gas form without converting into a liquid. The liquid phase is essentially skipped. In order for this conversion to work, energy must be supplied.

M & M candies are an example of a kind of energy. When we eat M & M candies what are we consuming? Calories. What is a calorie and how does it relate to the power of water?

A calorie is a measure of heat energy. It is also the energy necessary to raise one gram of water to one degree Celsius at atmospheric pressure.

Celsius is a unit of measurement for temperature. There are other temperature scales, such as the Kelvin system and Fahrenheit. Why do we use Celsius?

Celsius is important because it focuses on the temperature point 0^o C and 100^o C, which are the points of freezing and boiling for water respectively.

What is temperature?

Temperature is the degree or the measurement of heat. It is very important to write the scale you are working with because each scale represents a different temperature range.

For example 0^o K (Kelvin) = -273 degrees.

What is the super power force of our planet? The sun. The sun is solar energy. The sun is nuclear energy from a nuclear explosion. The solar energy comes down as a bunch of rays.

There are three methods of transmitting energy; radiation, conduction, convection.

Convection:
Usually occurs in liquids and gases. Warm air released rises towards the ceiling, cool air will sink towards the ground. As long as we have an influx of air, we get a continual circular flow, convection current.

Note: Air in certain designs can move horizontally, which is referred to as a horizontal convection. We will go over examples later.

Conduction:
This is the transfer of energy from one object to another. Certain metals are better conductors then others. This is The earth is the largest recipient of energy. The earth can either receive the energy or bounce it back towards the source. For a given substance, the percentage of energy out of 100% that is not received and bounced back is the albedo of that substance.

For example, the albedo of a substance is 30%, that means that it reflects 30% of the energy and absorbs 70%. (100%-30% = 70%).

This can lead you to start asking, What is the albedo for a cloud? The ozone layer?

The absorbance of 70% of the energy will raise the temperature of the object. (get warmer)

In relation to the ozone layer, how does this work? The ozone layer filters out the harmful UV light. A small percent is deflected but most is absorbed. It never reaches the earth. In terms of reflecting, consider the words scatter and defraction. These terms will be explained next time.

Getting an ATTITUDE about LATITUDE, ALTITUDE and HYDROTUDE

Four questions to class --- can anyone answer all four?

1. What day, at noon, in Washington DC has the longest shadow of the year?

2. What is the shortest day of the year in Washington, DC?

3. What day (date) of the year are we closest to the sun?

3. What day in Washington DC is the sun directly overhead at high noon?

(Answers to questions 1-3: all the same answer --- December 20-22 (the first day of winter; answer to #4: Never --- the sun is never directly overhead at noon in Washington, DC.)

What do you know about the seasons and how they work?

Seasonal changes have been very important in the history of humankind. Prior to the Julian calendar, records of the seasons and observed celebrations were based on patterns of the sun. In pre-Julian times, the new year began with spring. Even today, look at the Chinese New Year and annual "events" based on weather changes:

1. Fish make runs up rivers in early spring, as waters begin to warm. Note that many streams of water around here are called "runs".

2. Farmers are awaiting the first frost-free day to begin plantings.

3. Cherry Blossom Festival

How do (deciduous) trees "wake up"? Temperature does this. In the DC area, after December 21, each day receives 2 more minutes of solar energy --- one minute in the morning, and one in the evening. The further north you go, the amount of gained solar energy increases even more. (If go south, the opposite is true.)

Looking at Seasons

Seasons are based on the increase or decrease of the amount of sunlight received on Earth. The tilt of the Earth’s axis with respect to its position with the Sun causes the amounts of solar energy to change seasonally. This tilt is 23.5⁰. At the summer solstice, this tilt is towards the Sun; at the winter solstice, the tilt is away from the Sun.

Equinox: the date when the day and night of a 24 hour period are the same. They occur when the Earth is at a 90 degree angle to the sun. (See diagram above.) The dates differ for the seasons in the two hemispheres.

The Earth is closer to the sun in the winter, therefore, its position is a key to global change. Humankind seems to ritualistically "follow the sun". Examples of vernal festivals, "honoring" the sun and following old sun calendars:

• Annual Sun Festival in Newgrange, Ireland
  
• Mayan ruins
  
• Stonehenge
  
• Easter Islands
  
• Anasazi of SW United States
  
• Easter
  
• Passover
  
• College spring break and beach trips

All societies, cultures and religions have a solar or seasonal aspect in their histories.

Latitude and the amount of sunlight: Impacts

Latitude (need definition): If known, you can predict what will happen with temperature, winds, solar exposure controls, hot and cold desert belts, coral reef bands, ocean currents, El Nino, agricultural belts. All of these are in place due to the amount of nuclear energy received from the sun.

The movement of the Earth’s movements and tilt can be plotted based on the Sun’s path.

Milan Milankovitch studied these calculations, and came up with a hypothesis about effects of a different angle for the tilt of the Earth. Based on his calculations, there have been three major cycles of planetary tilt, spanning angles of tilt from 21 ⁰ to 27⁰. These cycles occur every 21,000 – 42,000 – 100,000 years. Whenever the tilt changes, there are major temperature changes in varying locations all over Earth.

See the following internet sites for more information:

http://riemann.usno.navy.mil/AA/data/docs/EarthSeasons.html

http://riemann.usno.navy.mil/AA/data/docs/AltAz.html

Question to class: Is it people or science that is causing changes in temperature?

The Orographic Effect

The orographic effect looks at the changes that occur when the altitude changes, specifically in reference to the effects of large mountains on climate. Mountains and water have a big effect on solar energy. ("oro" = mountain) We can especially see this in our country in California and Hawaii. Weather tends to be wet and humid in the land area between large bodies of water and mountains. On the other side of the mountains --- the side away from the water --- it is a dry climate.

An example of this locally is to look at storms approaching the DC area. Snow storms coming from the west are frequently stopped at the mountains in the western part of the area; hurricanes from the coast usually don’t make it over the mountains. Snow from the coast tends to be much wetter than any snow that does make it over the mountains.

Buildings can act in the same way. This is called the urban orographic effect.

On a global scale, if a mountain is tall enough, it can get glaciers at its top, no matter what the temperature at its foot. Examples of this can be found in Africa and South America. In these cases, altitude is much more important than latitude.

For more about glaciers at the equator, see the following reference:

http://www.pbs.org/wgbh/nova/ice

The effects of water and land temperatures cause ocean and land breezes as a function of the result of the differences between the temperatures of a large volume of water and the land bordering it. Seabreezes occur during the day, from water to land, when air is warmed by the land and rises, being replaced by the cooler air over the water. The opposite occurs at night, from land to sea, when landbreezes occur, being formed by the air being warmer over the water and rising and being displaced by the air over the now cooled land.

Fog is also a function of land and water differences, especially in New England.

El Nino is a function of coastal water coming up to land masses, as it affects upwelling, or the process by which water rises from a lower to a higher depth, and downwelling, in which the water has a downward movement. Upwelling brings up the cooler lower waters, and occurs with La Nina; downwelling takes the warmer upper waters to a deeper depth, and occurs with El Nino. Natives watch the birds and fish for these changes. Fish like cooler water, and birds like fish!

One theory for El Nino "blames" the Himalayas Mountains, as well as for other temperature changes. In other words, these changes have been internal, within the Earth, rather than external, caused by humankind. These mountains have created a whole new orographic effect over the last 60,000,000 years. Scientists are still working on the causes and effects of global climate changes. (See above internet site.)

(Note: Check March 1999 issue of the National Geographic for article on El Nino by Curt Suplee.)

We must look at whether what happens is a cycle (periodic reoccurrences of phenomena) or an event (a unique occurrence).

Energy and Humans

Questions to class:

1. How much energy are we getting today?
2. How long has this been going on?
3. What sort of impact will it have on you? (where you live, types of clothing, etc.)

Question to class: Where would the ideal place be to live on Earth? Answer: Equator, with dark skin.

As one migrates further north, things change. However, most people on Earth live on areas to wither side of the equator, Most food is grown here, too. When rainforests are destroyed, hidden heat is lost, thus changing other areas, also.

The key point is how much sunlight are you getting? This is what affects people.

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