In the name of Allah most gracious most merciful.
Assalaamualaikum wa rahmatuallahi wa barakatahu
This hadith deals with the height of Adam alai salaam.[ 60 cubits]
Sahih Al-Bukhari HadithHadith 4.544 Narrated byAbu Huraira
Allah's Apostle said, "The first group of people who will enter Paradise, will be glittering like the full moon and those who will follow them, will
glitter like the most brilliant star in the sky. They will not urinate, relieve nature, spit, or have any nasal secretions. Their combs will be of
gold, and their sweat will smell like musk. The aloes-wood will be used in their centers. Their wives will be houris. All of them will look alike and
will resemble their father Adam (in statute), sixty cubits tall."
Sahih Al-Bukhari HadithHadith 4.543 Narrated byAbu Huraira
The Prophet said, "Allah created Adam, making him 60 cubits tall. When He created him, He said to him, "Go and greet that group of angels, and listen
to their reply, for it will be your greeting (salutation) and the greeting (salutation) of your offspring." So, Adam said (to the angels), As-Salamu
Alaikum (i.e. Peace be upon you). The angels said, "As-salamu Alaika wa Rahmatu-l-lahi" (i.e. Peace and Allah's Mercy be upon you). Thus the angels
added to Adam's salutation the expression, 'Wa Rahmatu-l-lahi.' Any person who will enter Paradise will resemble Adam (in appearance and figure).
People have been decreasing in stature since Adam's creation.
The hadith says when Allah subhanawatala created Adam in heaven,his height was 60 cubits.When he was in heaven he met angels and greeted them,the
hadith talks about Adam alai salaam in heaven & and earth is not mentioned at all.And when humans after judgement day will enter heaven then they will
all be 60 cubits as the height of Adam alai salaam when he was in jannah including him as well.And in the end the Hadith states people have been
decreasing in stature since adam's creation.The decreasing height is on earth alone.because Adam alai salaam's offsprings are born on earth .
here is an example,not much in detail though ,just covering few years.
The age by which final adult height is achieved has been decreasing continuously during the last 200 years.(in England)
excerpts taken from www.bismikaallahuma.org
Allah knows best.