Unit 6: Properties of the AtmosphereAtmospheric Variables

Do Now: What is Weather? _________________________________________________________________________________________________________

What are the major components of the atmosphere?ESRT

____________ ________________________ ____________

What is the structure of the atmosphere? Complete Worksheet

List and define the conditions of the atmosphere that interest meteorologists the most. (Review book Chapter 6)

Temperature:_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Unit 6-7: Properties of the Atmosphere (cont.)The Station Model

Station Model Hot Tips: 1. Sky cover “pies” sweep quarters of the circle

like a clock’s hand.2. The Wind flag staff always points into the wind

or the wind blows down the flag staff into the circle.

3. Wind speed short feather = 5 knots ( 2kts)4. If pressure trend is negative, three hours ago,

the pressure was highera) current pressure and pressure trend will always be to tenth (no decimals on the station model)

5. Maximum pressure range: 960mb to 1050mb

More Helpful Hints:__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Unit 6: Properties of the AtmosphereAtmospheric Pressure

Do Now:Pressure: The force caused by the weight of the atmosphere on a given surface area. The units for air pressure can be expressed as:mb ______________________lbs/in2 ____________________Inches or cm of (Hg)________________

Demo: Draw arrows on the following diagram to represent the confining pressure on the surface of the can. Let arrow length represent the strength of the pressure field.

Equal inside and out Air removed, higher pressure outside

Pressure is affected by air density directly.

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Unit 6: Properties of the AtmosphereAtmospheric Moisture

Do Now: Use the following words to indicate the processes in the simplified water cycle diagram below.Remember – clouds are made of liquid water

1. _________________

2. _________________

3. _________________

4. _________________

5. _________________

1. Sources of Atmospheric Moisture:a) Evaporation (Vaporization) = liquid gasb) Transpiration – process by which

photosynthetic organisms release water vapor (mostly plants and algae)

c) Evapotranspiration – combination of a & b d) The oceans cover >70% of the Earth’s surface

and are the primary source of atmospheric moisture.

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Word BankCondensation Precipitation Energy SourceStratosphere Evaporation Water Source

2. Energy is absorbed into the atmosphere when water changes from a liquid to a gas.

Amount of energy gained (by the atmosphere) during vaporization =___________cal/g - see ESRT page 1

Energy source for vaporization: _________________

3. Factors Affecting Evaporation Rate

a) available energy (Sun or Heat)________________________________________________________________

b) surface area exposed (Tumbling, Hanging, Brushing)

__________________________________________________________________

b) air movement (Wind or Fan)

__________________________________________________________________

c) amount of moisture already in the air (Humidity)

__________________________________________________________

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Unit 6: Properties of the AtmosphereAtmospheric Moisture (cont.)

Water Vapor Fact #1: As air temperature increases, its ability to hold water vapor also increases.See flask diagrams handout and RB figure 6-11.

Water Vapor Fact #2: Water vapor is less dense than air, so “humid” air is generally less dense than dry air. (Remember, less dense = less pressure)

4. Absolute Humidity – the volume of water vapor in a given volume of air Ex: 3 ml/m3

5. Relative Humidity – the ratio of the amount of water vapor in the air compared to the maximum amount the air can hold at that temperature, or “How full of moisture the air is”. The total amount of WV the air can hold is known as its capacity.

Rh is reported as a percent (%) Rh of 100% is considered saturated

Air temperature and Rh are ____________ related.

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Unit 6: Properties of the AtmosphereAtmospheric Moisture (cont.)

The temperature at which air becomes saturated is called the dewpoint temperature (DPT).Relative humidity can be measured by an instrument called a hygrometer. The simplest hygrometer -a sling psychrometer - consists of two thermometers mounted together with a handle attached on a chain. Of course, those are expensive so YOU get some cheap flimsy ones. One thermometer is ordinary and is called the dry bulb thermometer,  the other has a wet cloth wick over its bulb and is called a wet-bulb thermometer. When a reading is to be taken, the dry bulb is read first, then the wet bulb thermometer with its wick is dipped in water and then the instrument is whirled around and usually flies apart.   During the whirling, the water evaporates from the wick, cooling the wet-bulb thermometer. Then the temperatures of the wet bulb is read. If the surrounding air is dry, more moisture evaporates from the wick, cooling the wet-bulb thermometer more so there is a greater difference between the temperatures of the two thermometers. If the surrounding air is holding as much moisture as possible - if the relative humidity is 100% - there is no difference between the two temperatures.

Meteorologists have worked out charts of these differences for each degree of temperature so that the observer can find relative humidity easily. See ESRT.

Indoors: Outdoors:

Dry Bulb__________ Dry Bulb__________

Wet Bulb__________ Wet Bulb__________

Rh________________ Rh________________

DPT______________ DPT_______________

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Unit 6: Properties of the AtmosphereAtmospheric PressureFactors Affecting Air Pressure:

Humidity vs. Pressure Temperature vs. Pressure

Air Density vs. Pressure Altitude vs. Pressure

1. Air with high density weighs more causing __________ pressure. Air density and pressure are _________ related.

2. As the amount of water vapor in the air _________________ the air density ______________ causing the pressure to __________________. Humid air is ________ dense than dry air causing _______pressure.

3. As the air temperature increases, the density of the air _____________ causing the air pressure to __________________. Warm air is _________ dense than cold air.

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As DRY air rises, its temp decreases about 5.5F per 1000 ft. This is known as the Dry Adiabatic Lapse Rate. As SATURATED (wet) air rises, it cools at 3.5F per 1000 ft. This difference results from water vapor in the saturated air condensing. As the vapor condenses, it releases _____cal/g of heat into the air causing the WET adiabatic lapse rate to be less (3.5F).

4. As altitude increases, the pressure __________________ (see ______ chart page ___).

Unit 6: Properties of the AtmosphereAdiabatic Cooling/Heating

Adiabatic Cooling and Heating:a) As a gas expands, its

temperature decreases.b) As a gas compresses, its

temperature __________.

Energy is neither added nor removed; during expansion, the heat energy is spread out over a larger volume resulting in a lower measured temperature.

As air rises, it expands and cools. If the air cools below its dewpoint, condensation will occur. This happens at a particular elevation, depending upon the air temperature and humidity.

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Water vapor requires a surface for condensation. This surface is called a condensation nucleus.

Explain this drawing of the Orographic Effect:Why is rain only falling on one side of this mountain?

________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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Flask, room temperature

Flask, cooling on an ice cube, no condensation nuclei

Flask, cooling on an ice cube, WITH condensation nuclei

Shade in the flask containing condensation

Summary: How do clouds form?

Warm air _________ and expands. As the air expands it ____________. If the air cools to it’s ___________temperature, the air becomes saturated with ____________ ____________.

More cooling results in ________________, creating a cloud. Clouds are made of _____________ (phase) water.

Unit 6: Properties of the AtmosphereAtmospheric Pressure/Wind

Wind – the horizontal movement of air parallel to the Earth’s surface (vector quantity).

1. _________________ differences between two places cause density differences in the air.

2. Density differences cause air pressure differences (see notes pages 3 & 8)

3. Pressure differences cause air to move horizontally from Higher to Lower pressure.

4. Winds are named by the direction they come _________________!

Pressure Gradient – difference in air pressure over a certain ________. Write formula here:

1. The closer the isobars are together, the stronger the pressure gradient force resulting in _____________ wind speeds. (see handout)

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The Coriolis effect deflects winds to the __________ in the northern hemisphere, and to the _______ in the __________ _____________.The Coriolis effect results from Earth’s rotation.

Unit 6: Properties of the AtmosphereCirculation In the Atmosphere

1. Convergence – winds come together and rise – caused by LOW pressure

2. Divergence – air is sinking and spreads out at the surface – caused by HIGH pressure.

H L

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High pressure circulation is clockwise and diverging. Low pressure circulation is _________________ and ______________.

Unit 6: Properties of the AtmosphereCirculation In the Atmosphere

1. Atmospheric circulation distributes the sun’s energy by the process of convection. Convection cells may exist on a local and global scale.

2. Local Winds – see “Land and Sea Breezes” handout

3. Global/Planetary winds – a series of wind belts in the troposphere blowing horizontally away from areas of divergence (____pressure) toward areas of convergence (_____pressure). See ESRT page ____. These winds curve to the ________ in the _______ __________________ and to the ___________ in the _________ ___________________ due to the ___________ ___________.

Complete “Global Wind Patterns” handout.

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4. Surface Ocean Currents -movement of surface ocean water caused directly by winds transferring some of their energy to the water. __________ are/is also caused by the wind on the water’s surface. Sea ESRT.

Summary Regents Questions:

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Simple model of circulation assumingno axial tilt, no rotation (Coriolis), and allsurface materials equal.

A more realistic model of actual circulation. Draw arrows depicting the “Hadley Cells” around the question marks.