WeatherWeatherWeathering the WeatherWeathering the Weather

Whether the weather be fineWhether the weather be fineOr whether the weather be Or whether the weather be

notnotWhether the weather be coldWhether the weather be coldOr whether the weather be Or whether the weather be

hothotWe’ll weather the weatherWe’ll weather the weather

Whatever the weatherWhatever the weatherWhether we like it or notWhether we like it or not

What is weather?What is weather?

Weather is the state of the atmosphere Weather is the state of the atmosphere at a specific place and time.at a specific place and time.

It is what is happening outside right now.It is what is happening outside right now. A few miles or a few minutes can change A few miles or a few minutes can change

the weather.the weather.

At any given time, the weather is fair in At any given time, the weather is fair in some places, while it rains or snows in some places, while it rains or snows in othersothers

What is the weather like today?What is the weather like today?

Why is weather important?Why is weather important?

The weather affects our lives every The weather affects our lives every day. day.

It can have an impact on what type of It can have an impact on what type of clothing we wear and how we spend clothing we wear and how we spend our free time. our free time.

Weather also affects agriculture, Weather also affects agriculture, transportation, and industry. transportation, and industry.

TemperatureTemperature Humidity Humidity Cloud Formation Cloud Formation Air Pressure Air Pressure Wind Direction & SpeedWind Direction & Speed

What factors affect weather?What factors affect weather?

TemperatureTemperature

The sun warms the earth’s surface and The sun warms the earth’s surface and therefore all the air above the surfacetherefore all the air above the surface

TemperatureTemperature - measure of how hot or - measure of how hot or cold the air is. cold the air is.

Remember, temperature is the Remember, temperature is the average motion (kinetic energy) of average motion (kinetic energy) of molecules, so…molecules, so…– high movement of molecules = high movement of molecules =

high temperature (hot)high temperature (hot)– low mlow movement of molecules = ovement of molecules =

low temperature (cold)low temperature (cold)

HumidityHumidity

Humidity –Humidity – the amount of water the amount of water vapor in the airvapor in the air

Would you go to the beach on a hot, humid day, or a cool, crisp day?

– Absolute humidityAbsolute humidity – measure of – measure of how much water vapor the air is how much water vapor the air is capable of holding. The hotter the capable of holding. The hotter the air is, the more moisture it can holdair is, the more moisture it can hold

– Relative humidityRelative humidity – measure of – measure of how much moisture there is actually how much moisture there is actually in the air – expressed as percentage in the air – expressed as percentage of absolute humidityof absolute humidity

Cloud FormationCloud Formation

With cold air, molecules move slower With cold air, molecules move slower so droplets of water can start to stick so droplets of water can start to stick together and form clouds - together and form clouds - condensationcondensation

Clouds form when water vapor Clouds form when water vapor condenses on dust particles in the aircondenses on dust particles in the air

Types of CloudsTypes of Clouds

CumulusCumulus – White, tall and puffyWhite, tall and puffy– Definite base, and Definite base, and

look like cotton ballslook like cotton balls

StratusStratus

– flat shapes flat shapes – stack up in layersstack up in layers– low level and cover low level and cover

most of the skymost of the sky

CirrusCirrus– Thin curves with no clear Thin curves with no clear

shape found high in the shape found high in the skysky

– wispy, feathery cloudswispy, feathery clouds– made of ice crystalsmade of ice crystals

CumulonimbusCumulonimbus– tall, puffy, and graytall, puffy, and gray– may bring thunder and may bring thunder and

lightning.lightning.

There are many more types of clouds. Basic There are many more types of clouds. Basic categories are used to classify them. Their categories are used to classify them. Their names combined to form over 10 different cloud names combined to form over 10 different cloud types.types.

Air PressureAir Pressure

Air pressure is the weight of the air Air pressure is the weight of the air pushing downpushing down

High pressure – cool air descends toward High pressure – cool air descends toward the Earth’s surface. the Earth’s surface. – Usually means clear sunny daysUsually means clear sunny days

Low pressure – warm air rises upward into Low pressure – warm air rises upward into the atmosphere the atmosphere – Usually means high humidity, clouds, Usually means high humidity, clouds,

rainrain

Looking at a weather map, you’ll notice the Looking at a weather map, you’ll notice the air masses constantly moving around.air masses constantly moving around.

The boundaries of these areas are called The boundaries of these areas are called frontsfronts

WindWind

Air moves from areas where air Air moves from areas where air pressure is relatively high to areas pressure is relatively high to areas where air pressure is relatively low. where air pressure is relatively low. This movement of air is what we call This movement of air is what we call wind.wind.

Winds are measured by direction and Winds are measured by direction and speedspeed

A wind chill is the A wind chill is the cooling in cooling in temperatures that the wind causestemperatures that the wind causes