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WEATHER

WEATHER . Weather vs. Climate Weather – the atmospheric conditions over a relatively short period of time Climate – the weather in some location averaged over a long period of time. Weather Measurements.

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WEATHER

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  1. WEATHER Weather vs. Climate Weather – the atmospheric conditions over a relatively short period of time Climate – the weather in some location averaged over a long period of time

  2. Weather Measurements What weather phenomena do we need to measure? What instruments do we use to measure them?

  3. Coe Lake Weather MeasurementsTradition & Electronic • Temperature • Atmospheric Pressure • Rainfall • Relative Humidity • Wind Direction • Wind Speed

  4. CLOUD TYPE REVIEW • These cloud types should be familiar to you. Write down the website if you need to go back to revisit them. http://asd-www.larc.nasa.gov/SCOOL/cldchart.html • “Cirrus” or “Cirro” – high (base above 6000 m) • “Alto” – mid (base 2000 m-6000 m) • No prefix – low clouds

  5. Temperature • Two scales – Celsius & Fahrenheit • http://www.sciencemadesimple.com/conversions.html • Boiling Point of Water 212 °F 100 °C • Average Body Temperature 98.6 °F 37 °C • Hot Summer Day 85 °F 29.4 °C • Average Room Temperature 68 °F 20 °C • Cool Fall Day 55 °F 12.8 °C • Warm Winter Day 40 °F 4.4 °C • Freezing point of Water 32 °F 0 °C • You must know ABT & ART in °C • You must know the BP & FP of Water in °C

  6. Thermometers • We use a variety of thermometers at Coe Lake • All measurements will be done in Metric! • Digital thermometers • Thermometers with various scale markings that make it challenging for students to read • “What’s Hot & What’s Not?” • “Weatherwise”

  7. Thermometers

  8. ATMOSPHERIC PRESSURE • Atmospheric pressure (or air pressure) is the weight of Earth's atmosphere on the surface at a given location and is generated by the downward force of Earth's gravity. • Atmospheric pressure depends on the amount of air above the location where the measurement is taken, consequently the pressure drops as you go higher. • Also known as Barometric Pressure because it is measured with a barometer.

  9. Barometric Pressure Unit Craziness! • National Weather Service: • inches of Mercury (inHg) • mm of Mercury (mmHg) • hectoPascals (hPa) • A Pascal is the metric unit for air pressure and 100,920 Pa is equal to 1009.20 hPa • millibars (mb) (same as hPa)

  10. Average Atmospheric Pressure at Sea Level • In Weatherspeak: • 29.9 inHg • 1013.25 hPa • 1013.25 mb • In Chemspeak: • 101.325 kPa • 760 mmHg • 1.00 atm • 14.7 psi

  11. Barometers

  12. Rainfall (Snowfall) • Rainfall impacts all of us, from the lack of rain during times of drought to the dangers of flash floods when we receive too much rain too fast. • It is the depth of water reaching the ground, typically in inches or millimeters. • Rainfall rate • Light = 0.10 inches of rain per hour • Moderate = 0.10 to 0.30 inches of rain per hour • Heavy = over 0.30 inches of rain per hour

  13. Rainfall • An inch of rain is exactly that, water that is one inch deep. • One inch of rainfall equals 4.7 gallons of water per square yard or 22,650 gallons of water per acre! Wow! • Measured with a Rain Gauge.

  14. Rain Gauges

  15. Relative Humidity • The amount of moisture in the air relative to how much moisture the air can hold. • Temperature dependent. • Higher temperatures – the air can hold more moisture. (Think about hot, humid summer days…) • Lower temperatures – the air holds less moisture. (The relative humidity might be the same as a hot summer day, but less moisture will be in the air.)

  16. Relative Humidity • Humidity is measured with a hygrometer. • Relative humidity is measured with a Sling Psychrometer. • Humidity measurements can be used to calculate dew point and heat index.

  17. Relative Humidity Chart

  18. Heat Index

  19. Measuring Humidity

  20. Wind Measurement • Wind is the natural motion of the air roughly parallel to the Earth's surface. • It is caused by the unequal heating and cooling of the Earth and atmosphere by the sun, which produces differences in air pressure. • Air tends to flow from areas of higher pressure to lower pressure.

  21. Wind Measurement Wind occurs at all scales. • Global winds (trade winds) • Upper level winds (jet streams) • Synoptic winds (resulting from the pressure differences of surface air masses) • Local (mesoscale) winds (such as gust fronts) • Winds that develop because of geographical features (like sea breezes). • Winds also occur on a much smaller scale, for example dust devils or tornadoes.

  22. Wind Measurement Wind measurements are taken at a fixed location and measure two parameters: • Wind Speed – mph, kph, knots • Wind Direction – cardinal directions; always naming the wind for the direction from which it comes • EX: a SE wind comes from the southeast

  23. Wind Speed – Anemometer

  24. Wind Direction – Wind Vane

  25. What do you need to know? • What are the various weather phenomena and • What are the definitions? • What tool is used to measure it? • What metric unit is used to measure it? • Match the name of the cloud to its altitude using the correct prefixes (alto & cirro) • What are the metric and English (F) temperatures for the bp & mp of water, body temperature & room temperature? • What is the difference between weather and climate?

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