Weather & climate 1

Question 1

What is weather?

Answer 1

• —> condition of the atmosphere
• —> at a particular place and particular time
• —> shorter period of time

Question 2

What is climate?

Answer 2

• —> climate is the average condition of the atmosphere

- —> over a long period of time, usually over 30 years

Question 3

Elements of weather

Answer 3

Temp
Relative humidity
Clouds
Rainfall
Air pressure
Wind

Question 4

what is temp?

Answer 4

• —> degree of hotness/coldness of a place
• —> units: °C
• —> measured using digital thermometer and analogue
• —> high temp: >20°C
• —> low temp: <10°C

Question 5

mean daily temp

Answer 5

the sum of hourly temp divided by 24h

Question 6

Diurnal (daily) temp range

Answer 6

Diff btw max & min temp recorded in a day

Question 7

Mean (average) monthly temp

Answer 7

Average of daily temp recorded in a month

Question 8

annual (yearly) temp range

Answer 8

diff btw max & min mean monthly temp recorded in a year

Question 9

What is relative humidity

Answer 9

Ratio btw the actual amount of water vapour present in a mass of air and the max amount of water vapour the air could hold at a given temp

Question 10

what is relative humidity measure with

Answer 10

sling psychrometer

Question 11

relative humidity’s relationship with temperature

Answer 11

As temperature increases, relative humidity decreases

• —> Warm air can hold more water vapour than cool air
• —> When temp increases, the amount of water vapour in the air stays the same
• —> But the rise in temp makes the air more able to hold water vapour

Question 12

Saturation & condensation

Answer 12

Saturation

• —> relative humidity is 100%
• —> occurs at dew point temp
• —> condensation occurs at dew point temp

Condensation
—-> water vapour changes to liquid form by cooling

Question 13

How are clouds formed?

Answer 13

• —> earth is heated up
• —> Evaporation occurs (water to water vapour)
• —> At dew point temp, condensation occurs if there are tiny particles for the water vapour to condense on
• —> Condensation nuclei: tiny particles like dust
• —> water droplets in the air will bump into each other
• —> become larger in a process called coalescence

Question 14

What are clouds

Answer 14

• —> visible mass of water droplets/ice crystals suspended in the atmosphere
• —> water droplets eventually grow large enough to fall to the earth’s surface as precipitation

Question 15

what is rainfall

Answer 15

• —> water in any form that falls from the atmosphere to the surface of the earth
• —> precipitation includes: hail, snow, sleet (rain & snow) and rain
• —> high rainfall: >1500mm
• —> low rainfall: <250mm
• —> measured using rain gauge

Question 16

why does rain occur

Answer 16

• —> air instability

- —> tendency of parcel of air to rise rather than remain in its original position

Question 17

process of convectional rain

Answer 17

• —> earth’s surface heated intensely
• —> warm surface heats the air around it
• —> air becomes unstable
• —> air expands & rises
• —> as the air rises, the temp drops
• —> air cools to dew point temp
• —> condensation
• —> clouds form
• —> water droplets heavy & large enough
• —> fall to the ground as rain

Question 18

process of relief rain

Answer 18

• —> moist air passes over the sea
• —> arrives at the coast
• —> air is forced to rise up windward side of mountain
• —> air is forced to cool
• —> air reaches dew point temp
• —> condensation
• —> clouds form
• —> water droplets heavy and large enough
• —> fall as rain on the windward side
• —> leeward side: usually dry as most rain has fallen on the windward side

Question 19

what is land breeze

Answer 19

----> blows from land to sea
At night:
----> land loses heat faster than water bodies
----> sea has a higher temp
----> sea has lower air pressure
----> air moves from area of high pressure to low pressure
----> moves from sea to land
----> forms land breeze

Question 20

what is sea breeze?

Answer 20

----> blows from sea to land
Day:
----> land heats up faster than water bodies
----> land has a higher temp
----> land has higher pressure
----> air moves from area of high pressure to low pressure
----> air moves from land to sea
----> sea breeze

Question 21

What are monsoon winds

Answer 21

• —> regional wind patterns that reverse direction seasonally
• —> brings seasonal changes in precipitation
• —> affected by the Coriolis effect

Question 22

southwest monsoon

Answer 22

Takes place btw June and Sept

Northern hemisphere:

• —> summer
• —> air over central Asia heats up
• —> air expands and rises
• —> low pressure

Southern hemisphere:

• —> winter
• —> air becomes cold and dense
• —> high pressure
• —> Diff in pressure btw Central Asia & Australia
• —> Air moves from Australia to Indian sub-continent and Central Asia
• —> Southeast monsoon winds
• —> wind crosses the equator
• —> Coriolis effect deflects the wind to the right
• —> winds become southwest monsoon winds
• —> wind warm up
• —> picks up moisture in Indian ocean
• —> brings heavy rain to Indian-subcontinent

Question 23

Northeast monsoon

Answer 23

takes place btw Oct & Feb

Northern hemisphere

• —> winter
• —> air becomes cold & dense
• —> high pressure

Southern hemisphere

• —> summer
• —> air heats up
• —> low pressure
• —> air moves from area of higher pressure to lower pressure
• —> air moves from central Asia to Australia
• —> northeast monsoon winds
• —> winds cross the equator
• —> Coriolis effect deflects them to the left
• —> northwest monsoon winds
• —> warm up
• —> warm air picks up moisture
• —> brings heavy rain to Australia