Mammatus clouds

http://blog.chicagoweathercenter.com/assets_c/2012/04/tornebstgs041412.html

Date Time(cdt)

Wind(mph) Weather Sky Cond.

Temperature (ºF)

RelativeHumidityAir Dwpt

07 06:55 E 8 Fair CLR 39 32 76%

07 06:35 NE 3 Fair CLR 37 31 80%

07 06:15 NE 6 Fair CLR 38 32 77%

07 05:55 E 7 Fair CLR 38 32 80%

07 05:35 E 5 Fair CLR 37 32 83%

07 05:15 NE 6 Fair CLR 36 32 84%

http://spaceweathergallery.com/indiv_upload.php?upload_id=96099

http://spaceweathergallery.com/full_image.php?image_name=Alan-Dyer-Mars-and-Spica-Rising-April-5-2014_1396828305.jpg&PHPSESSID=jiksbn310hq0cbpshug7cofql1

Ch 18 Measuring Humidity Lab

Problem: How can relative humidity be determined?

You will be able to calculate the humidity of the air using data and a hygrometer.

Ch 18 Lab

• Relative humidity is a measurement used to describe water vapor in the air.

• In general, it expresses how close the air is to saturation.

• In this lab, you will use a psychrometer and a data table to determine the relative humidity of air.

25˚C = 20 g/kgRelative Humidity (%) = 5 ÷ 20 = .25 RH = .25 x 100 = 25%

Part B: Determining Relative Humidity Using a Psychrometer

• A psychrometer consists of two thermometers—a wet-bulb thermometer and a dry-bulb thermometer.

• The wet-bulb thermometer has a cloth wick that is wet with water and spun for about 1 minute.

• Relative humidity is determined by calculating the difference in the temperature reading between the dry-bulb temperature and the wet-bulb temperature and using Data Table 2.

Wet-bulb Dry-bulb

4) Suppose a dry-bulb temperature is measured as 20°C, and a wet-bulb temperature is 14°C.

• Read the relative humidity from Data Table 2.• Write it down.

5)• Make wet-bulb and dry-bulb temperature measurements for

the air in your classroom and the air outside. – Dry-bulb = plain thermometer– Wet-bulb = wet cloth thermometer in front of fan (2 min).

• Use Data Table 3 to record your measurements. • Use your measurements and Data Table 2 to determine the

relative humidity inside and outside.

Wet-bulb Dry-bulb