Topic 4- Motions of Earth, Moon, and Sun



Topic 7- Weather

Weather – variables that change in a given area

(such as temperature, air pressure, wind, moisture, cloud cover, precipitation, and storms)

- occurs mainly in the troposphere

In the reference tables on page ________:

[pic]

A. Causes of Weather

1. Energy from the Sun

a. Through the seasons it heats our planet, some parts more and some less.

[pic]

b. This uneven heating causes earth’s atmosphere to react and become a gigantic engine that produces lots of different types of weather.

c. Insolation

• Incoming Solar Radiation – the portion of the Sun’s radiation that reaches the earth’s atmosphere.

d. Atmospheric Temperature

• Air Temperature is a measurement of the amount of kinetic energy (movement) of the particles

Hot Air Cold Air

• Air temperature is usually measured using a thermometer

• Most of the world uses the Celsius scale, but in the United States we still use Fahrenheit.

• (In science classes we use Celsius)

• converting between Celsius, Fahrenheit, and Kelvin scales:

in the reference tables on page ____

Human body temperature

_____ oF = _____ oC = _____ oK

Water Boils

_____ oF = _____ oC = _____ oK

Room Temperature

_____ oF = _____ oC = _____ oK

Ice Melts

_____ oF = _____ oC = _____ oK

e. Heat transfer

i. Conduction

• The flame’s heat causes molecules in the pan’s bottom to vibrate faster making it hotter. These vibrating molecules collide with their neighboring molecules, making them vibrate faster too. After a while the molecules in the pan’s handle are vibrating so fast that it is too hot to touch.

• In your own words:

_______________________________________________________________________________________________________________________________________________________________________________

ii. Convection

• The heat in the pan especially near the flame causes the molecules of water at the bottom of the pan to vibrate faster, making it hotter. The hotter water becomes less dense and rises, and surrounding cooler, more dense water sinks to replace it. A circular pattern of movement develops within the water. This up and down movement eventually heats all of the water.

• In your own words:

_______________________________________________________________________________________________________________________________________________________________________________

iii. Radiation

• The heat in the pan radiates heat in the form of waves to the surrounding air. (Air is a poor conductor of heat.)

• In your own words:

_______________________________________________________________________________________________________________________________________________________________________________

f. Heating and Cooling of Air by Expansion and Contraction

• When a gas expands, its temperature decreases.

So… when air rises, it expands and the air temperature decreases.

• When a gas is compressed, it’s temperature increases.

So… when air descends, it is compressed and the air temperature increases.

In the reference tables on page ____

g. Factors that effect the amount and rate of heating.

• Angle of sunlight and duration (length of daylight)

• Land heats faster and cools faster than water does

(if it changes temperature fast it has a low specific heat; also if it changes temperature slow it has a high specific heat)

on the reference table on page______

[pic]

Liquid water has the highest specific heat of anything on Earth!! Water is Weird!!

• Color

[pic]

Dark objects heat faster than light objects

• Texture

[pic]

Rough objects heat faster than smooth objects

h. Mapping a Temperature Field

• Isotherms are lines that connect points of equal temperature.

• IOn the map above: The greatest temperature gradient is between Richmond and Hattaras which is indicated because the isotherms are closest together.

• Temperature gradient calculation from Cincinnati to Chicago:

2. Air Pressure (aka: Atmospheric pressure or barometric pressure)

a. measurement of the weight of the atmosphere pushing down on an area. (The force of gravity causes the air to have weight.)

b. Atmospheric Pressure Scale

In the reference tables on pg ____

Conversions:

997 mb = __________

_________ = 30.15 in.

1006 mb = __________

982 mb = __________

_________ = 29.53 in.

_________ = 30.21in.

1019 mb = _________

c. The effect of temperature on air pressure

As the temperature of the air increases, the air pressure decreases.

Vs.

Cold air Hot Air

High Pressure Low Pressure

d. The effect of moisture on air pressure

As the amount of moisture in the air increases, the air pressure decreases.

e. The effect of altitude on air pressure

[pic]

As altitude increases, the air pressure decreases (less air pushing down).

In the reference tables pg _____

[pic]

f. Mapping an air pressure field

• Isobars are lines that connect points of equal air pressure.

• On weather maps, barometric pressure is represented by a three-digit number to the upper right of the circle. The circle represents a city on the map.

Special rules to follow:

053

1) a decimal point is omitted between the last two digits on the right.

2) The number 9 or 10 is omitted in front of this number.

If the original number is above 500, place a 9 in front.

If it is below 500, place a 10 in front. (Secret trick: use whichever will give a result closest to 1000mb)

Example: 053 --> __________

778 --> __________

521 --> __________

925 --> __________

• On the map on the next page draw isobars for 1004, 1008, 1012, 1016, and 1020 millibars.

Identify the center of the high pressure region by placing an H on the map.

Identify the center of the low pressure region by placing an L on the map.

3. Wind

a. Causes of Winds (what makes the wind blow?)

• Uneven heating of the earth’s surface

• Examples:

o Land vs water

o Dark forest vs. snowy field

o Poles vs. equator

b. Sea Breeze vs. Land Breeze

• Sea breeze

[pic]

• Land Breeze

[pic]

c. Wind Direction

• Winds always blow from High pressure to Low pressure (The flow go from high to low)

• Map view:

• Side/profile view

Chicago Buffalo Boston

d. Wind Speed

• The speed of the wind is determined by the difference in the air pressure

Big difference in air pressure = high winds

Isobar lines are close together = high winds

e. Global Winds

• The unequal heating of the different parts of the earth creates different air pressures, which then results in winds.

• Cooler air is more dense and sinks, warmer air is less dense and rises.

Global winds on earth (if earth didn’t spin or rotate)

But, because earth does spin, the coriolis effect changes the winds to look like this:

This can be found where? ________

4. Moisture

[pic]

a. Changes in State

In reference tables on page ____

• Evaporation: water to water vapor

It requires 540 calories of energy to convert

1 gram of liquid water to water vapor.

• Condensation: gas to a liquid

It requires 540 calories of energy to convert

1 gram of gas to a liquid.

• Melting: solid to a liquid

It requires 80 calories of energy to convert

1 gram of solid to a liquid.

• Freezing: liquid water to solid ice

It requires 80 calories of energy to convert

1 gram of liquid water to solid ice.

[pic]

b. Humidity is the general term used to describe the amount of water vapor in the air.

c. Temperature determines the amount of water vapor the air can hold.

As air temperature increases the amount of water vapor the air can hold increases.

d. Saturation

Occurs when the air is holding as much water vapor as it can at that temperature.

(Like a full sponge)

e. Factors that effect Evaporation

• Temperature - as temp increases the rate of evaporation increases

• Humidity – as the humidity increases the rate of evaporation decreases

• Wind – as wind speed increases the rate of evaporation increases

• Surface Area – as surface area increases the rate of evaporation increases

5. Dew Point

The temperature that the air must be cooled to in order to reach saturation.

a. The dew point of the air is measured by using a sling psychrometer.

b. use the dew point chart in the reference tables on pg ______

Determine the dew point for the following:

|Dry Bulb Temp | | | | | | | |

| |22oC |22oC |20oC |15oC |9oC |8oC |17oC |

|Wet Bulb Temp | | | | | | | |

| |20oC |13oC |14oC |12oC |3oC |6oC |17oC |

|Dew Point | | | | | | | |

6. Relative Humidity

The ratio between the actual amount of water in the air and the amount of water that the air could hold at that temperature.

a. The effect of air temperature on Relative Humidity

10oC 20oC 30oC

if the temperature increases and the moisture stays the same then the relative humidity decreases

b. use the dew point chart in the reference tables on pg ______

[pic]

Determine the relative humidity for the following:

|Dry Bulb Temp | | | | | | | |

| |20oC |8oC |22oC |22oC |15oC |15oC |3oC |

|Wet Bulb Temp | | | | | | | |

| |14oC |6oC |13oC |20oC |12oC |15oC |-1oC |

|Relative Humidity | | | | | | | |

7. Cloud Formation

a. Clouds are tiny droplets of liquid water or tiny ice crystals suspended in the air.

b. Conditions needed:

• Water vapor

• Cooling air (becoming more saturated)

• Dust particles (aka: condensation nuclei)

II. Air Masses and Fronts

A. Air Masses are large bodies of air that have similar characteristics such as temperature, moisture, and pressure.

B. They are named based on a combination of the temperature and moisture.

C. Types of Air Masses:

a. Tropical – originates in the tropics (low latitudes).

It is associated with high temperatures.

b. Polar – originates in polar regions (high latitudes)

It is associated with low temperatures.

c. Arctic – originates in ice covered arctic regions (in the winter only.)

It is associated with very cold air.

d. Continental – originates over land masses

It is associated with dry air.

e. Maritime – originates over water.

It is associated with wet air.

|Symbol |Name of Air Mass |Characteristics |

|cP | | |

|mT | | |

|cT | | |

|mP | | |

It’s on the reference tables on pg _____

[pic]

D. Illustrated below are the source regions of air masses that affect the weather of North America. The arrows indicate the paths that these air masses usually follow.

[pic]

III. Fronts

The leading edge of an air mass

A. Types of Fronts & Symbols

|Type of Front |Map Symbol |

|Cold | |

|Warm | |

|Stationary | |

|Occluded | |

It’s on the reference tables on pg ______

[pic]

A view of the front from the side

IV. Areas of Rainfall

A. Anywhere on Earth where air rises

1. Windward side of a mountain

2. Doldrums – the equator region of the Earth.

3. Low Pressure Systems

4. Along a Front

[pic]

-----------------------

Warm Front

L

H

L

H

The particles are close together and bounce into each other more

The particles are farther apart so they don’t bounce into each other as much

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