weather and climate change (precipitation)

Question 1

relative humidity

Answer 1

60/100 the humidity compared to the total that can be achieved

Question 2

absolute humidity

Answer 2

amount of water vapour present in specific amt of air

Question 3

relationship of temp and relative humidity

Answer 3

temp inc, relative humidity dec (inversely related)

Question 4

why temp inc, relative humidity dec?

Answer 4

temp inc, air expands, total humidity achievable inc, but humidity remains the same, therefore, less relative humidity

Question 5

saturation

Answer 5

relative humidity is 100%

Question 6

the temperature at which saturation occurs

Answer 6

dew point temp

Question 7

where does dew point temp usually take place?

Answer 7

higher in the atmosphere

Question 8

what areas are very humid?

Answer 8

equatorial zone

Question 9

why is it so humid in the tropics?

Answer 9

1. recieve large amounts of solar radiation which inc the rate of evaporation.
2. the presence of vegetation increases evapotranspiration and increases humidity too.
3. nearby oceans and lakes facilitate evaporation.

Question 10

how to measure humidity

Answer 10

dry bulb (dry muslin sleeve)
wet bulb (wet muslin sleeve)

Question 11

dry bulb

Answer 11

atmosphere temp

Question 12

wet bulb

Answer 12

water evaporates bulb cools. produces temp diff between 2 thermometers. amt of evaporation and cooling of the bulb depends on relative humidity.

Question 13

how to calculate RH with dry and wet bulb

Answer 13

use the calculation table to compare dry and wet bulb temperature differences (wet bulb depression)

Question 14

sling psychrometer procedure

Answer 14

1 Ensure that there is water in the enclosure
2 Hold the Sling psychrometer above your head when swinging
3 Swing it for 1 minute
4 Read and record the temperature on the two thermometers (Wet and Dry)
5 Repeat steps 1 to 4
6 Calculate the difference between wet and dry bulb
7 Refer to the conversion table to read R.H

Question 15

rationale for ensuring that there ins water in the enclosure sling psychrometer

Answer 15

for the wet bulb thermometer to function

Question 16

rationale for holding the sling psychrometer above your head when swinging

Answer 16

• So that it is far from your body and does not pick up body heat that affects reading
• Safety reasons for not hitting your friend

Question 17

rationale for swinging sling psychrometer for 1 minute

Answer 17

gives sling psychrometer enough time to stabilise reading

Question 18

reason for repeating sling psychrometer steps

Answer 18

more readings to average out inconsistencies, and discrepancies, ensures accuracy

Question 19

weather tracker

Answer 19

• Wind Speed
• Air/Water/Snow temperature
• Wind Chill
• Relative Humidity
• Heat Stress Index
• Dewpoint Temp
• Wet Bulb Temp
• Barometric Pressure
• Altitude
• Density Altitude

Question 20

clouds

Answer 20

a visible mass of water droplets or ice crystals that are suspended in the atmosphere

Question 21

cloud formation

Answer 21

1. HEAT causes water to EVAPORATE into WATER VAPOUR
2. WARM AIR containing water vapour starts to RISE
3. Air is COOLED RAPIDLY as it rises because TEMPERATURE DECREASES WITH ALTITUDE
4. As the parcel of air rises in the atmosphere, the TEMPERATURE FALS AND RELATIVE HUMIDITY RISES (cool air holds less water vapour compared to warm air)
5. (condensation)
6. Water droplet condenses on dust particles which act as
   CONDENSATION NUCLEI, tiny water droplets form around
   these particles.
7. COALESCENCE takes place

Question 22

coalescence

Answer 22

Water droplets collide with each other and merge into larger water droplets

Question 23

condensation

Answer 23

When relative humidity reaches 100% at HIGH ALTITUDES,
the air becomes SATURATED and the excess water vapour
ceases to exist as gas and changes back to water

Question 24

okta scale

Answer 24

shaded area represents the portion of the sky that is covered by clouds

Question 25

precipitation

Answer 25

water in any form that falls from the atmosphere to the surface of the earth (hail, snow, rain)

Question 26

types of rain

Answer 26

convectional rain relief/orographic rain frontal rain

Question 27

convectional rain process

Answer 27

1. The surface of the earth is HEATED INTENSELY which warms the AIR near the surface 2. The air EXPANDS and RISES as it is heated, its CAPACITY to hold water vapour also INCREASES 3. As warm air rises, it COOLS gradually and can no longer hold as much water vapour, the RELATIVE HUMIDITY of the parcel of air INCREASES 4. At a certain altitude, the relative humidity of the air reaches 100%. CONDENSATION occurs and tiny droplets of water condense around the dust particles in the air 5. Tiny water droplets COALESCENCE to form clouds. High evaporation and rapid condensation result in cumulonimbus clouds to form, leading to convectional rain

Question 28

what is convectional rain usually associated with

Answer 28

convectional rain (thunderstorms) are usually associated with lightning and thunder

Question 29

convectional rainfall intensity

Answer 29

intense: a large amount of water falls as rain over a short period of time

Question 30

relief rain (orographic rain) process

Answer 30

1. A PARCEL OF AIR blows across a WATER BODY and picks up MOISTURE 2. As this parcel of air approaches a mountain, the moist air is forced to RAISE UP THE SLOPE 3. As warm air rises, it COOLS gradually and can no longer hold as much water vapour, the relative humidity of the parcel of air increases 4. At a certain altitude, the relative humidity of the air reaches 100%. CONDENSATION occurs and tiny droplets of water condense around the dust particles in the air 5. Tiny water droplets merge COALESCENCE to form clouds. 6. When the water droplets are heavy enough, they fall as rain on the WINDWARD SIDE

Question 31

windward side

Answer 31

the direction that the wind is blowing

Question 32

what happens to the non-windward side of the mountain

Answer 32

it is DRY. it is called the LEEWARD SIDE or the RAIN SHADOW AREA because the parcel of air decreases in altitude, warms up and can hold more water vapour (relative humidity decreases)

Question 33

how to measure rainfall

Answer 33

rain gauge

Question 34

where to place a rain gauge?

Answer 34

1. On short grass in an open area 2. Far away from buildings and other obstructions. 3. Sunk into the ground with the rim 30 cm above ground 4. NOT on concrete ground

Question 35

why should you place a rain gauge on short grass in an open area?

Answer 35

to prevent water collected on leaves of trees from dripping in

Question 36

why should you place a rain gauge far away from buildings and other obstructions?

Answer 36

to prevent water collected on roofs of buildings from dripping in

Question 37

why should you place a rain gauge sunk into the ground with the rim 30 cm above ground?

Answer 37

to prevent topping over by a human or other living things

Question 38

why can you not place a rain gauge on the concrete ground?

Answer 38

to prevent rainwater from splashing into it from the hard surface of the concrete

Question 39

how to use weather tracker

Answer 39

1. Switch on the weather tracker, switch to the intended mode 2. Hold the weather tracker at one- arm’s length 3. Ensure that the sensor and the fan is not covered 4. For wind speed: Hold weather tracker above head.

Question 40

switch on weather tracker switch to intended mode rationale

Answer 40

Allow for accurate recording of data

Question 41

Hold the weather tracker at one- arm’s length rationale

Answer 41

Prevent the sensors from picking up body heat or moisture

Question 42

Ensure that the sensor and the fan is not covered rationale

Answer 42

Allow for accurate recording of data

Question 43

For wind speed: Hold weather tracker above head rationale

Answer 43

Allow air to flow freely to record accurate wind speed data