Weather

SOL 6.3 and 6.6

Identify and explain the composition, properties, layers, and structure of the atmosphere. Analyze the properties that can be observed and measured to predict air quality: air pressure,

humidity, moisture, and temperature and air quality. Examine evidence (charts and graphs) that atmospheric properties can be studied to predict

atmospheric conditions and weather hazards Analyze the role of the sun in the heating and cooling that forms clouds and order the sequence

of events that takes place in the formation of a cloud Relate the three states of water to the water cycle. Compare and contrast types of precipitation, cloud types, and relate cloud types to weather

conditions and their location in the atmosphere Map the movement of cold and warm fronts, and interpret their effects on observable weather

conditions. Interpret basic weather maps, and make forecasts based on the information presented.

Compare and contrast weather-related phenomena including thunderstorms, tornados, hurricanes, and drought.

Assess the use of technology in predicting, monitoring, and recording atmospheric phenomena. Weather satellites role

Analyze and explain some of the effects that natural events (forest fires and volcanic eruptions) and human activities may have on weather, atmosphere, and climate.

Analyze and explain the difference in average winter temperatures among areas in central and western Virginia and cities and counties along the Chesapeake Bay and Atlantic coast.

Earths Energy Budget

• The Earth’s atmosphere is 78% nitrogen, 21% oxygen, and the rest trace gases including; argon, carbon dioxide, and water vapor

Earth’s Energy Budget:51% absorbed by the surface19% absorbed by atmosphere

Remaining 30% lost back to space…COPY THE PICTURE

1. The Earth receives only a very small portion of the sun’s energy, yet this energy is responsible for powering the motion of the atmosphere, the oceans, and many processes at the Earth’s surface.

2. Incoming solar radiation is in close balance with the energy that leaves the atmosphere; otherwise the Earth would heat up or cool down. Excess carbon dioxide and other gases may disrupt this balance, creating a Greenhouse Effect.

3. About 1/3 of the sun’s incoming energy is reflected back out to space. About 1/2 of the energy striking the Earth is absorbed by the surface.

4. The Earth’s surface is heated unequally. This is due to the tilt of Earth on its axis. The equator gets more sun the poles get less.

5. Radiation and convection from the surface transfer heat energy. This energy powers the global circulation of the atmosphere and the oceans on our planet. Remember that heat rises, cools and sinks.

6. The sun is responsible for most energy sources on Earth

1. How does the amount of energy Earth receives from the sun compare with the energy the leaves Earth?

2. What do you predict would happen if there was a shortage of incoming solar radiation?

3. What would happen if Earth retained more thermal energy?

Energy Transfers

• Radiation brings all of the energy to the Earth from the sun

• Convection currents redistribute the energy throughout the atmosphere and the oceans.

Currents in the Atmosphere and Oceans

• Convection currents redistribute the energy all over the planet that comes from the sun. The average mean temperature is fairly warm because of these currents.

Air Pressure

• Air pressure is the amount of air pushing down on us. It is measured with a barometer

• Low pressure means lousy weather, cool & rainy

• High pressure means fair weather, warm & sunny

• Increase in altitude = decrease in air pressure

Humidity

• Humidity is the amount of water vapor in the air• The more humid the air is the more uncomfortable you feel• 100% humidity is fog (stratus cloud formed on the ground)• It is measured with a psychrometer or hygrometer• Dew point is the temperature at which the air becomes

100% humid

Atmospheric Layers

• Layers are defined by changes of temperature• Troposphere: weather takes place & clouds are found

• Stratosphere: jet stream and the ozone layer is found

• Mesosphere: coldest and stops most meteorites (burn up)

• Thermosphere: top most layer, it is divided into the ionosphere (northern lights) and the exosphere (satellites)

Why Protect the Air?Watch & Summarize in your notes

The Westerlies dominate the weather in the United States.Trade winds are warm, steady breezes that blow continuously.Wweak surface winds are @ the equator, this area is called the

doldrums.

Winds are named from the direction in which they travel from

Horse Latitudes

Doldrums

Easterlies

Cloud Formation

Types of Clouds

What is weather?

• Weather is caused by the unequal heating of the Earth’s surface. Warm air rises and cool air sinks

• Warm air = high pressure

• Cold air = low pressure

How to read a weather map

Thunderstorms• Thunderstorms – cold meets warm front forming heavy

rainstorms with thunder and lightning.

• When the air is heated by lightning it expands quickly resulting in loud sound waves (thunder).

• Lightning – sudden discharge of electricity between cloud and cloud; cloud and ground. Leading cause of forest fires. Can strike people, animals, or building.

• Safety – avoid open spaces outside; don’t go under trees for shelter, avoid sinks, bathtubs, televisions, and telephones while inside during a lightning storm.

Hurricane, Cyclone, Typhoon• Hurricanes – power cyclones that form over tropical areas.

• Typhoon – hurricane that forms over the Pacific ocean.

• The eye of the storm is calm but the winds reach speeds of 74 to over 155 m/hr.

• High winds, storm surges, flooding, LOW PRESSURE

• Most powerful of all storms.

Tornadoes

• Very destructive & most violent

• Rotating counter-clock wise, funnel-shaped

• Develops in low, heavy cumulonimbus clouds.

• Acts like a giant vacuum cleaner

• LOW PRESSURE!!!

• Associated with severe thunderstorms

• Occur in tornado alley in the United States only

Weather Symbols

High Pressure System: Sunny weather will often occur under high pressure

Low Pressure System: lousy weather, spins counter clockwise

Cold Front:. When the cold front passes the temperature drops and the rising air along the front can bring precipitation

Warm Front can bring precipitation especially in the region where the warm front is approaching.

A stationary front has a little or no movement, rain for days

Occluded Front: cold front that overtakes a warm front. They commonly occur close to a maturing low pressure system

Weather Maps

Isobars-connect areas of equal pressure

Weather Instruments:Copy when I pause

Make sure you know:

1. Warm, moist air is less dense than cold, dry air, so it rises relative to colder, drier air.

2. Warm, moist air rises and actually gives off some heat as the moisture condenses

3. Air exerts pressure. Air pressure decreases with altitude. 4. Forest fires and volcanic eruptions are two natural processes

that affect the Earth’s atmosphere. Many gaseous compounds & particles are released into the atmosphere by human activity.

5. The amount of heat energy, water vapor, and the pressure of the air largely determine what the weather conditions are.

6. Air pressure is measured in millibars7. The Coriolis Effect makes winds rotate to the right (clockwise)

in the Northern Hemisphere