WEATHER WEATHER

Weather vs. ClimateWeather vs. Climate WeatherWeather – the atmospheric – the atmospheric conditions over a relatively short conditions over a relatively short period of timeperiod of time

Climate Climate – the weather in some – the weather in some location averaged over a long period location averaged over a long period of timeof time

Weather Weather MeasurementsMeasurementsWhat weather phenomena do we What weather phenomena do we

need to measure? What need to measure? What instruments do we use to instruments do we use to measure them?measure them?

Coe Lake Weather Coe Lake Weather MeasurementsMeasurements Tradition & ElectronicTradition & Electronic

TemperatureTemperature Atmospheric PressureAtmospheric Pressure RainfallRainfall Relative HumidityRelative Humidity Wind Direction Wind Direction Wind SpeedWind Speed

CLOUD TYPE REVIEWCLOUD TYPE REVIEW

These cloud types should be These cloud types should be familiar to you. Write down the familiar to you. Write down the website if you need to go back to website if you need to go back to revisit them.revisit them.

http://asd-www.larc.nasa.gov/SCOOL/cldchart.hthttp://asd-www.larc.nasa.gov/SCOOL/cldchart.htmlml

““Cirrus” or “Cirro” – high (base above 6000 m)Cirrus” or “Cirro” – high (base above 6000 m) ““Alto” – mid (base 2000 m-6000 m)Alto” – mid (base 2000 m-6000 m) No prefix – low cloudsNo prefix – low clouds

TemperatureTemperature

Two scalesTwo scales – Celsius & Fahrenheit – Celsius & Fahrenheit http://www.sciencemadesimple.com/conversions.htmlhttp://www.sciencemadesimple.com/conversions.html

– Boiling Point of WaterBoiling Point of Water 212 212 °F°F 100 °C100 °C– Average Body TemperatureAverage Body Temperature 98.6 °F98.6 °F 37 °C37 °C– Hot Summer DayHot Summer Day 85 °F85 °F 29.4 29.4

°C°C– Average Room TemperatureAverage Room Temperature 68 °F68 °F 20 °C20 °C– Cool Fall DayCool Fall Day 55 °F55 °F 12.8 °C12.8 °C– Warm Winter DayWarm Winter Day 40 °F40 °F 4.4 °C4.4 °C– Freezing point of WaterFreezing point of Water 32 °F32 °F 0 °C0 °C

You must know ABT & ART in You must know ABT & ART in °C°C You must know the BP & FP of Water in °CYou must know the BP & FP of Water in °C

ThermometersThermometers

We use a variety of thermometers We use a variety of thermometers at Coe Lakeat Coe Lake– All measurements will be done in All measurements will be done in

Metric!Metric!– Digital thermometersDigital thermometers– Thermometers with various scale Thermometers with various scale

markings that make it challenging for markings that make it challenging for students to readstudents to read

– ““What’s Hot & What’s Not?”What’s Hot & What’s Not?”– ““Weatherwise”Weatherwise”

ThermometersThermometers

ATMOSPHERIC ATMOSPHERIC PRESSUREPRESSURE

Atmospheric pressure (or air pressure) is the Atmospheric pressure (or air pressure) is the weight of Earth's atmosphere on the surface weight of Earth's atmosphere on the surface at a given location and is generated by the at a given location and is generated by the downward force of Earth's gravity. downward force of Earth's gravity.

Atmospheric pressure depends on the Atmospheric pressure depends on the amount of air above the location where the amount of air above the location where the measurement is taken, consequently the measurement is taken, consequently the pressure drops as you go higher. pressure drops as you go higher.

Also known as Barometric Pressure because Also known as Barometric Pressure because it is measured with a barometer.it is measured with a barometer.

Barometric Pressure Barometric Pressure Unit Craziness!Unit Craziness!

National Weather Service: National Weather Service: – inches of Mercury (inHg)inches of Mercury (inHg) – mm of Mercury (mmHg)mm of Mercury (mmHg)– hectoPascals (hPa)hectoPascals (hPa)

A Pascal is the metric unit for air A Pascal is the metric unit for air pressure and 100,920 Pa is equal to pressure and 100,920 Pa is equal to 1009.20 hPa1009.20 hPa

– millibars (mb) (same as hPa)millibars (mb) (same as hPa)

Average Atmospheric Average Atmospheric Pressure at Sea LevelPressure at Sea Level

In Weatherspeak:In Weatherspeak:– 29.9 inHg29.9 inHg– 1013.25 hPa1013.25 hPa– 1013.25 mb1013.25 mb

In Chemspeak:In Chemspeak:– 101.325 kPa101.325 kPa– 760 mmHg760 mmHg– 1.00 atm1.00 atm– 14.7 psi14.7 psi

BarometersBarometers

Rainfall (Snowfall)Rainfall (Snowfall)

Rainfall impacts all of us, from the lack Rainfall impacts all of us, from the lack of rain during times of drought to the of rain during times of drought to the dangers of flash floods when we receive dangers of flash floods when we receive too much rain too fast.too much rain too fast.

It is the depth of water reaching the It is the depth of water reaching the ground, typically in inches or ground, typically in inches or millimeters.millimeters.

Rainfall rateRainfall rate– Light = 0.10 inches of rain per hour Light = 0.10 inches of rain per hour – Moderate = 0.10 to 0.30 inches of rain per Moderate = 0.10 to 0.30 inches of rain per

hour hour – Heavy = over 0.30 inches of rain per hour Heavy = over 0.30 inches of rain per hour

RainfallRainfall An inch of rain is exactly that, An inch of rain is exactly that,

water that is one inch deep. water that is one inch deep.

One inch of rainfall equals 4.7 One inch of rainfall equals 4.7 gallons of water per square yard or gallons of water per square yard or 22,650 gallons of water per acre! 22,650 gallons of water per acre! Wow!Wow!

Measured with a Rain Gauge.Measured with a Rain Gauge.

Rain GaugesRain Gauges

Relative Relative HumidityHumidity

The amount of moisture in the air The amount of moisture in the air relative to how much moisture the air relative to how much moisture the air can hold.can hold.

Temperature dependent.Temperature dependent. Higher temperaturesHigher temperatures – the air can hold – the air can hold

more moisture. (Think about hot, more moisture. (Think about hot, humid summer days…)humid summer days…)

Lower temperaturesLower temperatures – the air holds less – the air holds less moisture. (The relative humidity might moisture. (The relative humidity might be the same as a hot summer day, but be the same as a hot summer day, but less moisture will be in the air.)less moisture will be in the air.)

Relative Relative HumidityHumidity Humidity is measured with a Humidity is measured with a

hygrometer.hygrometer.

Relative humidity is measured with Relative humidity is measured with a Sling Psychrometer.a Sling Psychrometer.

Humidity measurements can be Humidity measurements can be used to calculate dew point and used to calculate dew point and heat index.heat index.

Relative Humidity Relative Humidity ChartChart

   

   

   

Heat IndexHeat Index

Measuring Measuring HumidityHumidity

Wind Wind MeasurementMeasurement

Wind is the natural motion of the air Wind is the natural motion of the air roughly parallel to the Earth's surface.roughly parallel to the Earth's surface.

It is caused by the unequal heating It is caused by the unequal heating and cooling of the Earth and and cooling of the Earth and atmosphere by the sun, which atmosphere by the sun, which produces differences in air pressure.produces differences in air pressure.

Air tends to flow from areas of higher Air tends to flow from areas of higher pressure to lower pressure. pressure to lower pressure.

Wind Wind MeasurementMeasurementWind occurs at all scales. Wind occurs at all scales. Global winds (trade winds)Global winds (trade winds) Upper level winds (jet streams)Upper level winds (jet streams) Synoptic winds (resulting from the pressure Synoptic winds (resulting from the pressure

differences of surface air masses) differences of surface air masses) Local (mesoscale) winds (such as gust fronts)Local (mesoscale) winds (such as gust fronts) Winds that develop because of geographical Winds that develop because of geographical

features (like sea breezes). features (like sea breezes). Winds also occur on a much smaller scale, for Winds also occur on a much smaller scale, for

example dust devils or tornadoes.example dust devils or tornadoes.

Wind Wind MeasurementMeasurementWind measurements are taken at a Wind measurements are taken at a

fixed location and measure two fixed location and measure two parameters:parameters:

Wind Speed – mph, kph, knotsWind Speed – mph, kph, knots Wind Direction – cardinal directions; Wind Direction – cardinal directions;

always naming the wind for the always naming the wind for the direction from which it comesdirection from which it comes– EX: a SE wind comes from the southeastEX: a SE wind comes from the southeast

Wind Speed – Wind Speed –

AnemometerAnemometer

Wind Direction – Wind Wind Direction – Wind VaneVane

What do you need to What do you need to know?know?

What are the various weather phenomena What are the various weather phenomena andand– What are the definitions?What are the definitions?– What tool is used to measure it?What tool is used to measure it?– What metric unit is used to measure it?What metric unit is used to measure it?

Match the name of the cloud to its altitude Match the name of the cloud to its altitude using the correct prefixes (alto & cirro)using the correct prefixes (alto & cirro)

What are the metric and English (F) What are the metric and English (F) temperatures for the bp & mp of water, temperatures for the bp & mp of water, body temperature & room temperature?body temperature & room temperature?

What is the difference between weather What is the difference between weather and climate?and climate?