Weather

@ SAG - Marek - '24 (P3)

A barometer measures

air pressure

Air or barometric pressure is caused by

the weight of the air

Cold air is high pressure because

the molecules are close together, sinks, and compresses (heavy)

Hot air is low pressure because

the molecules are far apart, expands, and cools (room for H20)

An anemometer measures

wind speed

Wind vane measures

wind direction

Wind is caused by

differences in air pressure

Isobars close together indicate

rough winds

Isobars far apart indicate

calm winds

The weather in a high is

happy, nice, cool and dry (sunny and no precipitation)

The weather in a low is

lousy, bad, warm and wet (cloudy and precipitation)

The circulation around a low pressure system is

Low, Inward, Counter Clockwise (LICC)

The circulation around a high pressure system is

High, Outward, Clockwise (HOC)

Sea Breeze

daytime, land is hot (Low Pressure), ocean is cold (High Pressure), winds go H -> L

Land breeze occurs at

night, land is cool (High Pressure), ocean is warm (Low Pressure), winds go L -> H

Coriolis Effect

winds and ocean currents deflected due to Earth's rotation

Sling psychrometer has a wet and dry bulb to measure

dew point and relative humidity

The close the air temperature is to the dew point

the greater the chance of precipitation

Dew Point temperature is the

temperature at which the air is saturated (filled) with water

Relative humidity is the

percent of water in the air

!00% Relative Humidity means that there is

precipitation, clouds, and/or fog

Warm air is capable of holding more

water vapor than cold air

Clouds form when

warm, moist air rises, expands, cools and condenses (at the dew point)

Cloud droplets from on tiny dust particles in the air called

condensation nuclei

Weather systems in the US usually move

from West to East (with a hook to the NorthEast)

The 500 Rule says

over 500 add a 9, below 500 add a 10, and always add a decimal

Source region of a cold and dry (cP) air mass

Central Canada

Source of a warm and moist (mT) air mass

Gulf of Mexico (warm waters)

Warm air rises because

it is less dense than cold air (molecules are more compact in cold air)

At the cold front air is

very unstable and thunderstorms occur (short, heavy rain)

In from of a warm front air is

stable and long drizzles occur (long, light rain)

Hurricanes form

over warm oceans in summer and autumn

Hurricanes lose strength

as they move over land or cool water

Tornadoes are

short lived (less than a minute) and small in size

In which temperature zone is most of the water vapor found and where weather occurs?

Troposphere

Temperature is the measure of

average kinetic energy and how fast the molecules move

Isotherms

lines that connect palace of equal temperature

Instrument used to measure temperature

thermometer

Temperature can be recorded in

Fahrenheit, Celsius, Kelvin

Isobars

lines that connect places of equal barometric pressure

Factors Affecting Air Pressure

Temperature, Water Vapor (Humidity), Altitude

How are winds named?

From the direction they come from

Instrument used to measure wind speed / anemometer

anemometer

The clock is high

the counter is low

Instruments used to determine relative humidity

hygrometer and sling psychrometer

Dry bulb

air temperature

Wet bulb

temperature an air parcel coded by evaporation of water

Condensation

change of phase from water vapor to liquid water

3 Things Needed for Condensation to Occur

1. Water vapor must be present

2. Air must be saturated

3. Condensation nuclei

Warm air rises because it is

less dense

Cold air sinks because it is

more dense

What does precipitation do for the environment?

Cleans the atmosphere

Where does the energy for weather originate?

Insolation from the Sun

In the United States, the general direction that weather systems move is towards the

East

Air masses

large region of the atmosphere with uniform temperature and humidity

Continental Polar (cP)

dry and cold

Continental Tropical (cT)

dry and warm

Maritime Polar (mP)

wet and cold

Maritime Tropical (mT)

wet and warm

Continental Arctic (cA)

dry and very cold

Which covers a greater geographic area, hurricanes or tornadoes?

Hurricanes

In which type of pressure system do hurricanes occur?

Low Pressure System

Fronts

boundary between two air masses

Cold front

passes quickly with violent weathers, cold air is behind the front, cold air pushes the warm moist air upward

Warm front

passes slowly with cloudy and rainy conditions for several hours, warm air is behind the front, warm but rainy conditions